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his ballistic tables (1881). But Mayevski appears to have recently Here is conclusive evidence of the perfect trustworthiness of the become a disciple of Krupp, from the diagram in NATURE, observations made, such as no other ballistic experiments have August 28, 1890 (p. 411), where the dotted line (1) represents afforded to my knowledge. When the readings of the screen roughly the resistance of the air to ogival-headed projectiles records required only such slight adjustments as those above given in my “ Final Report,” 1880 ; line (2) represents the law | indicated, there could be no reasonable doubt about the perfect of resistance deduced from these results by Major Ingalls, of the accuracy of the experiment, and the round was accordingly United States Artillery, which is similar to the law deduced by adopted as good in all cases, unless there was some known me (NATURE, April 29, 1886, p. 605); and line (3) represents disturbing cause, as when the bronze gun expanded, or where the results Mayevski professes to have deduced from Krupp's the gas check left the shot, &c. Meppen experiments. My law of resistance has been very Although the records are read off only to the 1/2000 of a closely followed throughout by Mayevski, as is evident from the second, we are able to express the coefficients of resistance diagram above referred to, which is suggestive of a free use of with much greater exactness through the employment of a long the parallel ruler. The main object of these proceedings seems range (1350 feet) where the only ahsolute errors in time possible to have been to persuade the world, and the Americans espe. are at the two extremities of the range, and the accuracy of cially, that Krupp guns are far superior to English guns, regard each of these readings is tested by the differencing. Supposing being had to the initial steadiness imparted by them to their the retarding force of the air, acting upon an ogival-headed projectiles. But this claim is unworthy of notice so far as it projectile moving in the direction of its axis with a velocity v f.s., depends upon the Meppen experiments with chronoscopes, the to be expressed by 2bv3, the values of 2000bw/d2 corpatent defects of some of which were pointed out in NATURE, responding to all velocities from 900 to 1700 f.s. were found by April 29, 1886 (p. 606). If, however, Government consider this experiment in 1867-68, where w denotes the weight of the matter worthy of investigation, there are simple practical methods projectile in pounds, and dits diameter in inches. Correspondof determining the comparative steadiness of projectiles fired ing to a velocity of 1200 f.s., the mean value of 2000bw/d2 from two or more guns.
was found to be o'000 1089. But to avoid the use of so many At present, my concern is with English guns only, and I wish decimal places, K was subsequently employed to denote to point out, as briefly as possible, (1) that my results obtained (1000)32bw/d2 = (1000) 3w12t]d?? = 108-9, where a't is the from English guns are quite correct; (2) that the coefficients of second difference of the times at which the shot passed successive resistance for each round are expressed by such a short unit of equi-distant screens I feet apart, with a velocity 1200 f.s. more time that they are made to appear more irregular than they are or less, and, in the case of the solid 5-inch shot it equals in reality, while the variation in their value is just what experi- o" '00124. From this it appears that for the specified shot the ment leads us to expect ; and (3) that when my mean coefficients time by which the unit of K is expressed is o".0000112 in 4%. are fairly used to calculate results of good experiments made with Considering the shortness of this unit of time, it seems very recent English guns, in calm weather, the agreement between natural that some variations should have been found in the calculation and experiment is perfectly satisfactory.
experimental values of K for any specified velocity, derived as My chronometric arrangements were made with a view to they have been from both hollow and solid projectiles fired with guard against the errors ci remaining magnetism, which is the various charges from 3, 5, 7, and 9-inch guns. If we turn to chief source of error in the measurement of extremely short
actual experiment, it is plain tbat the coefficients of resistance intervals of time by the help of electro-magnetism. All the for any given velocity cannot practically retain a constant value time-records were made by one electro-magnet, whose galvanic for all rounds. For do not we frequently read that shot are current was interrupted once a second by the swing of a half
noisy, or "unsteady” in their fight? There was much seconds clock pendulum ; and all the screen records were made unsteadiness in the Jubilee rounds; and Captain May, R.N., by another electro-magnet, whose galvanic current was being in speaking of experiments with recent guns, remarked, "the rapidly interrupted by a self-acting contact-breaker, till the pull
range of 500 yards is selected, because at this range shell which of the lanyard turned off the contact-breaker, and then fired the
start unsteadily will have steadied (that is if they ever do so), gun, after which the shot momentarily interrupted the galvanic &c.” It is, therefore, quite natural that exact expériment should current as it passed each of ten or more equi-distant screens. afford evidence of this unsteadiness. Also care was taken to reduce the strength of the galvanic cur- It now remains to test the value of my mean results by making rents, so as to leave each electro-magnet only just sufficient power use of them to calculate the ranges and times of flight of profor the performance of its appointed work. Under these circum- jectiles for comparison with the results of experiments made with stances it may be safely assumed that, if there were any errors recent guns. In 1879 some range tables of the 6'3-inch howitzer arising from remaining magnetism, in either clock or screen were forwarded to me to show that my coefficients for low records, they would be constant in each case, and therefore they / velocities did not give satisfactory results. As the muzzle velociwould have no injurious effect on the result obtained. The ties in these tables were 332, 507, 628, 697, 740, and 751 f.s., records on a 4-inch cylinder were read off by a vernier to the and the elevations varied from 50 to 40°, the trajectories were 1/3000 of its circunference; but as the scale of time was in much curved, so that my general tables were not applicable in general only 9 or 10 inches to the second, it may be concluded these cases. But when the ranges and times of flight were that the records were read off to the 1/2000 of a second at properly calculated by Bernoulli's method, experiment and calculeast.
İation were found to agree remarkably well. In the same way The accuracy of the time and of the screen records was
numerous German range tables (Krupp guns ?) were calculated for tested by differencing, when slight adjustments were applied to muzzle velocities varying from 380 to 774 f.s., which gave very render the first and second order of differences regular to an
satisfactory results in general. Although there was no allowadditional place of decimals. The following is a list of the
ance for jump or vertical drist in these calculations for low adjustments so applied in seven successive rounds, 146-152, muzzle velocities, the calculated often exceeded slightly the exwhich are fair samples of those applied in the other rounds
perimental ranges, showing that my resistances were perhaps a (1867-68). They are expressed in decimals of the unit read off little too low. The results of each of these comparisons--32 by the vernier, or of the 1/2000 of a second. In round 258 an English and 82 German-will be found in my “Final Report, example is given of the correction of an occasional erroneous
1880, pp. 45-47. For specimens of the best and worst results record at screen 6:-
of each kind, see NATURE, April 29, 1886 (p. 606). Now
Mayevski proposes to reduce these coefficients of resistance, Round 146.
258. already rather too low, by 20 per cent, more! (Ingalls,
pp. 29, 36).
In consequence of the Krupp scare, the authorities desired to have the accuracy of my results tested by practice on a long range, with a recent gun, and for this purpose they selected the
4-inch B.L. gun. Careful experiments were subsequently carried +04 +03
out with this gun (1887), which showed that my coefficients of +03
to'3 +329 resistance were perfectly satisfactory. But there was no real
necessity for any special experiments to be made with this gun, +07 + 0'2 +06
as its own range table was afterwards found to be abundantly sufficient for the purpose of testing my results. By calculating
trajectories carefully by Bernoulli's method, and then recalcu
o'o -07 tot +14
o'o to 2 --03
o'o - 01 +06 + 01 -01 +02 -o'r - 06 +07
to' -o'r -02 -ot to'2 -02 +16 To7
-02 +05 --01 -I'o - 02 +03 +04 - 07 +0! -02
-04 + 0*6
lating by the general tables the time of fight over the range he blamed for causing the projectiles to “issue from their guns already obtained, and also the striking velocity, it is found that with a very unsteady motion." He then went on to notice the the general tables may be used for elevations of the 4-inch gun large number of unsteady shot fired from the 9*2-inch gun in as high as 15°, or even more, with a muzzle velocity of 1900 f.s. 1888. I would also remind my critics that my coefficients of In this way the merest tyro may test my coefficients for his own resistance for velocities 1000 to 1700 f.s. were derived from exsatisfaction by calculating the times of flight over ranges of two periments made in 1867-68, while all those for velocities less or three miles given in any good range table for a high muzzle ihan 1000 f.s., and greater than 1700 f.s., were derived from exvelocity. The following are the results of such testing, usingperiments in 1878-80, carried out with some of the newest and the full extent of the range iable of the 4-inch B. L. gun, chosen best guns of the time. As conclusive evidence of the excellence by the authorities. Muzzle velocity, 1900 f. s. ; weight of ogival of the 3, 5, and 7-inch guns used in the early experiments, headed shot (two diameters), 25 pounds :
reference may be made to the fact that, from the results of the
experiments of 1867-68, I was able to deduce the Newtonian Range
6000. 7500 yds.
law of resistance for velocities 1350 to 1700 f. s. (Proc. R. A. Inst., 1871); and using the mean of the eight numerical coefficients
there given for velocities 1350, 1400, ... 1700 f.s., the numerical Horizontal muzzle vel. 1898.5 18950
18750 1853-5 1796 8 f.s. value of k will be found to be 143*9. Horizontal striking vel.' 11249
In 1879 experiments were made with a new Armstrong 6-inch Exp. time
B.L. gun, with velocities 1700 to 2250 f.s. (Reports, &c., 10'48 14.30
Part ii., 48); and again, in 1880, further experiments were
carried out with a new Armstrong 8-inch B.L. gun, with veloci. Difference
o'do +o‘26 +0'23
ties 2250 to 2800 f.s. (Final Report, 56). Combining these three sets of experiments, Major Ingalls found that the New
tonian law of resistance held good sor velocities 1330 10 2800 f.s., Here, as before, the calculated time is rather too short for where k = 142-1 (Ext. Bal., 36). I also deduced the same law velocities 1900 10 751 f.s. And if we allowed for a slight dimi. for velocities 1 300 to 2800 f.s., where k = 141.5 (NATURE, 1886, nution of the density of the air for the higher elevations, as we p. 606). And lastly, after a thorough revision of the reduction ought to do, the calculated would throughout fall very slightly of every round, I finally adopted the same law for velocities short of the experimental times of flight. Thus it is clear that above 1 300 f.s., where k = 111'2. my coefficients of resistance give perfectly satisfactory results Hence it appears that the early experiments of 1867-68 were when fairly tested by recent guns, chosen by Government, for so accurate that they gave a correct law of resistance for velocivelocities 330 to 751 f.s., and from 751 to 1900 f.s., or from iies 1350 to 1700 f.s., which has since been found to hold good 330 to 1900 f.s.
for velocities 1300 to 2800 f.s. ; and they also gave the coIn the same way we may use the model range table, carefully efficient k = 143'9 (with studded shot) sufficiently accurate for all prepared for the 12-inch B.L. gun by Captain May, R.N., for a practical purposes up to a velocity 2800 f.s. This is conclusive muzzle velocity 1892 f.s., and weight of shot 714 pounds (Proc. evidence of the steadiness of the shot in the early experiments, R. A. Inst., 1886, p. 356):
and of the accuracy of the method of reduction of those
But when those coefficients, which have been found correct by the use of the general tables, are employed to calculate
trajectories of eiongated shot moving with high velocities, the Experimental time
calculated ranges and times of flight gradually fall more and Calculated time
| more below those quantities given in the range tables, as the
elevation increases beyond 4° or 5°. These defects are generally
only small when the variation in the density of the air is taken Difference
o'019 into account ; but their presence indicates some slight disturbing
cause independent of the coefficients of resistance. We can Here, again, the calculated times of flight, being a trifle too | now make use of the exact method of calculating trajectories short, show that my coefficients of resistance are very slightly given by modern analysis, which was first published by J. too low.
Bernoulli. But this method applies with strictness only to the When coefficients tested in this manner give calculated times
motion of a spherical projectile, whose centre of gravity coincides of flight accurately over ranges gradually increasing up to two or
with its centre of figure. Many years ago Count St. Robert three miles, those coefficients must be correct for all practical
remarked : “On doit en conclure que les formules ordinaires de purposes, and they will give correctly the striking velocity and Ja balistique ne peuvent représenter la trajectoire décrite par les time of Alight for any other reasonable distance from the gun. projectiles allonga's.” (Balistique, p. 183). Also Mayevski has
The tables of “ Mayevski nach Siacci,” printed by Krupp, published an elaborate paper, "De l'Influence du Mouvement de 1883, may be used to calculate the times of flight of the shot Rotation sur la Trajectoire des Projectiles oblongs dans l'Air” fired from the 4-inch gun as above :
(Technologie Mil., 1866, pp. 1--150), which, however, leads to no useful result beyond showing that the author recognized the
effect of drift on the form of the trajectory. The chief cause Range
of the difficulty is this. For a short time after a steady elongated shot has left a rifled gun, the shot preserves the parallelism of
its axis, and in consequence of the action of gravity the point Experimental time
of the shot gradually rises above its trajectory till the resistance Calculated time
of the air causes the axis of the shot to begin to describe a
conical surface, with nearly constant vertical angle, about the Difference -0:38
moving tangent to the trajectory. Consequently, soon aster a -061
steady elongated shot leaves the muzzle of a rifled gun, the
resistance of the air acting on the inclined under side of the From this it is evident that the reduction of my coefficients pro- shot, begins to raise the shot bodily, and continues to do so posed by Mayevski on the strength of Krupp's experiments is until its axis has made one-fourth of a revolution about the uncalled for.
tangent to the trajectory. This vertical drift, near the gun, Again, it has been urged that my resistances ought to be causes the shot to move in its path as if it had been fired at a reduced in order to adapt them to recent guns, which, it is slightly increased elevation. Consequently, the observed range assumed, impart an increased degree of steadiness to their pro- and time of flight are each somewhat greater than that due to jectiles. But that assumption requires proof. After most the elevation at which the gun was laid. carefully testing the admirable range tables of the 4-inch and Another difficulty, common, however, to both spherical and 12-inch B.L. guns, I have failed to find any indication whatever elongated shot, is caused by the jump of the gun. In the range of increased steadiness in their projectiles. Besides, Admiral tables of the 4 and 12-inch guns above considered, six minutes Robert A. E. Scott wrote to the Morning Post (November 9, were allowed for the effect of jump for all elevations. But 1889), condemning the system of rifling the 110-ton gun, which | Major Ingalls remarks that "it varies in value from an angle
11 3'47 3'457
too small to be appreciable, to one of a degree of arc or even March 1888. Allowing 300 yards for jump and vertical drift, I ob.
: . It also varies somewhat with the angle of elevation.” tained a range of 19,736 yards. In April two rounds were fired In one of his examples he supposed the jump to be 22 to 23 with a velocity of 2375 f. s. at an elevation of 40°, which gave minutes. Although the jump and vertical drift are uncertain in ranges of 21,048 and 21,358 yards. My reply to this announceamount, they have considerable influence on the range and time ment, by return of post, was that the ranges were about 1500 of flight, and on this account the calculation of trajectories is a yards too great. In July the experiment was repeated, which decidedly unsatisfactory method of testing the coefficients of gave ranges of 20,236 and 20,210 yards, being a reduction of resistance of the air to elongated projectiles.
near 1000 yards. Two rounds fired at an elevation of 30° gave In the early days of elongated projectiles the vertical drist ranges of 17,500 and 18,344 yards ; two at 35o gave ranges of caused by the kite-like action" of the shot was duly recognized, 19,420 and 18,963 yards; and one at 45° gave a range of 21,800 but of late this disturbing force has been commonly ignored. yards. The times of Right have not been published. These For now, when a calculated range is shorter than the experi- great variations in range were due in part to unsteadiness in the mental range, it is at once assumed that the theoretical resistance motion of the shot, but chiefly to the prevalence of high favouris too high. This resistance is forthwith reduced so as to make able winds. the calculated agree with the experimental ranges, but seldom In order to test guns or coefficients of resistance in a satisfacis any care taken to compare the time of Might calculated with tory manner, calm weather is absolutely necessary. And if the this reduced resistance with the experimental time. It ought, shot is expected to rise to a height of two or three miles, trial however, to be remembered that, while a reduction of resistance balloons ought to be sent up to test the state of the currents in increases the range it diminishes the time of flight over a given the higher regions. Afterwards, wben good mean results of range. Major Ingalls has given a complete example of this experiments have been obtained, then, and not till then, may method of correcting my resistance (Problems, &c., p. 151). these mean results be used to test the results of calculation. For elevations of
Experiments ought not to be made at all unless precautions 20, 4°, 6°, 8°, and 10',
necessary to secure a correct result can be taken.
I have calculated a compleie range table for the 9'2 inch gun he found it necessary to reduce my coefficients by
for elevations 1°10 45°, according to the original programme 45 2'3
9.7 per cent.,
of the Ordnance Committee (NATURE, September 13, 1888, in order to obtain the experimental ranges by calculation ; and
p. 468), where the net results of calculation have been given. these reduced resistances gave the calculated times of Aight too
These ranges will require an addition perhaps of about 2 per
cent. for jump, vertical drift, &c., and a further i per cent. if short by
the ogival head be struck with a radius of two diameters instead 0":09 0":12 0":13 0":26 and o":42,
of one and a half, and the increment of time must be ruled by which proves clearly that the theoretical resistances had been this increment of range. too much reduced throughout. Also, if the method of cor.
My sole object having been to obtain the correct law of rerection pursued in the above example was correct, it would sistance of the air to the motion of projectiles, I was always follow that the coefficient of resistance is a function of the ready to consider any proposed correction. But my results, elevation, which is simply absurd.
obtained from numerous and most exact experiments, could be On the other hand, suppose we correct the elevation so as to changed only on perfectly satisfactory evidence. That evidence make the calculated agree with the experimental range, which
I have failed to obtain in any single case, so that my results seems to me to be a satisfactory approximate correction in such remain practically the same as they were given in my original cases. A careful calculation of the trajectory of an ogival- reports, 1868-80. I have recently published a revised account headed shot (two diameters) fired from the 4-inch B.L. gun, at
of all my experiments, accompanied by newly calculated general an elevation of 15°, gave a range of 6448 yards (185 yards too short tables, for both English and French measures, and other tables by the range table), and time of Alight' 20":46 (1":10 too short), required in the calculation of trajectories, according to the the density of the air having been supposed to vary with the results of modern analysis. With these helps I have now height of the shot. Now, corresponding to an elevation of thoroughly tested my final results by the use of range tables of 14° 16', the range table gives a range of 6448 yards, and time the 4-inch, 6'3-inch, and 12-inch guns, with the most gratifying of Alight 20":53. If we suppose that the elevation of the gun, results. And Major McClintock, R. A., has tested my coeffi14° 16', was practically increased by 44' by jump and vertical cients for small-arm bullets, with very satisfactory resulís (Proc. drift, we obtain an elevation of 150 for the initial direction of R.A. Inst., xii. 569). This evidence of the accuracy of my the shot. But, according to calculation, for an elevation of 15° results is the more valuable because it is derived from Governwe have found the range 6448 yards exactly, and the time of ment experiments, made for other purposes, which have manifight 20":46, which is only -0":07 in error, and the calculated festly been carried out with great care and ability. Anyone so horizontal striking velocity is 646 f.s. This, I maintain, is the disposed has the means to re-examine the whole matter for proper method of correction, because it corrects both range and himself. If there be not some error in my calculations, it time of flight, when there is no wind. Using the general tables appears that my results do not admit of any real improvement, and the horizontal muzzle velocity, the calculated time over
and consequently my labours in this matter may be considered 6448 yards is found to be 20":53, and horizontal striking velo- to have reached a satisfactory conclusion. city 647 f.s., where t = 0*967, the mean density of the air, as
F. BASHFORTH. the projectile would rise to a height of 1800 feet.
If the above be a correct view of what takes place, it follows FORTHCOMING SCIENTIFIC BOOKS. that the axis of the shot during its flight is inclined at such a small angle to the direction of ils motion, that the resistance of THE following is a list of scientific works which will be the air to its forward motion is not sensibly greater than when issued by various publishers in the course of the spring :it moves in the direction of its axis. But small as this angle Messrs. Macmillan and Co.:-“Essays on some Contromust be, we find evidence of the marked effect of the lateral | verted Questions," with a Prologue, by Prof. Huxley ; action of the air in causing the shot to drist to the right towards“ The Beauties of Nature,” by Sir John Lubbock, F.R.S., the end of the range. It is therefore to be expected that the illustrated; " Island Lise; or, The Phenomena and Causes resistance of the air, acting from below on the shot, soon after it of Insular Faunas and Floras," including a revision and leaves the gun will raise the shot upwards, and cause it to attempted solution of the problem of geological climates, move as if it had been fired at an elevation a little greater than by A. R. Wallace, with illustrations and maps, new and that at which the gun was laid.
cheaper edition ; “The Apodidæ,” a morphological study, The Ordnance Committee fired some ogival-headed projectiles by Henry M. Bernard, illustrated (Nature Series); **Exfrom a 9'2-inch wire gun at high elevations in 1888, prosessedly perimental Evolution,” by Henry de Varigny; " The Diseases to try whether calculations of trajectories at very long ranges are of Modern Lise," by B. W. Ricliardson, F.R.S., new and trustworthy. But before experimenting they invited calculators cheaper edition ; “The Geography of the British Colonies". 10 furnish them with the calculated range and time of fight of a 'Canada,” by George M. Dawson, “Australia and New 380-pound elongated shot fired at an elevation of 40° with a Zealand," by Alexander Sutherland (Macmillan's Geographical muzzle velocity of 2360 f.s. My calculations for an ogival head, Series); “Scientific Papers," by Oliver Heaviside; “The Algebra struck with a radius of one diameter and a half, gave a range of of Co-Planar Vectors and Trigonometry,” by R. B. Hayward, 19,436 yards, and time of flight 62":15, which were sent in in ! F.R.S., Assistant Master at Harrow; “Key and Students'
Companion to Higher Arithmetic and Elementary Mensura- Classes," by John Mills, numerous illustrations ; “Decorative tion,” by P. Goyen, Inspector of Schools, Dunedin, New Electricity," by Mrs. J. E. H. Gordon, with a chapter on Fire Zealand; " Arithmetic for Schools,” hy Barnard Smith, late Risks by J. E. H. Gordon, and numerous illustrations by Herbert Fellow and Bursar of St. Peter's College, Cambridge ; carefully Fell, engraved on wood by J. D. Cooper ; “Examination of revised in accordance with modern methods by W. H. H. Soils,” by W. T. Brannt. Hudson, Professor of Mathematics, King's College, London ; Messrs. George Philip and Son :--"Makers of Modern “Blowpipe Analysis," by J. Landauer, authorized English Thought ; or, Five Hundred Years' Struggle (A.D. 1200 to edition by J. Taylor and W. E. Kay, of the Owens College, A.D. 1699) between Science, Ignorance, and Superstition," by Manchester, new edition, thoroughly revised with the assistance David Nasmith, in two volumes; “Christopher Columbus,” by of Prof. Landauer ; “Nature's Story Books," I. “Sunshine," Clements R. Markham, Vol. VII. of “The World's Great liy Amy Johnson, illustrated.
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Botany for January and February is one by the late Dr. A. Training of the School Board for London, the City and Barclay on rust and mildews in India. He shows that the Guilds of London Institute, and the Worshipful Company of years in which the grain-crops were deficient have been those Drapers, with over 300 illustrations ; “Leather Work, Stamped, in which the climatal conditions were favourable to the growth of Moulded, and Cut, Cuir-Bouillé, Sewn, &c.,” by Charles G.
parasitic fungi. The chief enemy to wheat in India is Puccinia Leland, author of “Wood Carving," with numerous illus
rubigo-vera ; and it is an interesting fact that while the æcidiotrations. Whittaker's Library of Popular Science—“Mine- form of this Uredine occurs in Europe on Borraginaceous plants, ralogy,” by Dr. F. Hatch, with numerous illustrations ; “Che- no æcidium is known in India on any species of the order. Dr. mistry,” by T. Bolas, with many illustrations.
Barclay believes that its life-history has a different course in Messrs. Sampson Low and Co. :-" Answers to the Questions India from that taken in Europe. -Mr. W. G. Smith reports on Elementary Chemistry, Theoretical and Practical (Ordinary the progress at present made in the commission which he has Course), set at the Examinations of the Science and Art Depart-received from the Trustees of the British Museum to make a ment, South Kensington, 1887 to 1891," by John Mills, two vols.,
series of water-colour drawings of the whole of the British fully illustrated; “Chemistry for Students, consisting of a Series Basidiomycetes for the public gallery of the Department of of Lessons based on the Syllabus of the Science and Art De
Botany. -A series of papers is commenced in these numbers on partment, and specially designed to facilitate the experimental the first records of British flowering plants, by Mr. W. A. teaching of Elementary Chemistry in Schools and Evening Clarke.
The Bullettino of the Italian Botanical Society is now pub- where the two arrows had the same direction, energy was being lished apart from the Nuovo Giornale. The first number contains given to the system, and where the arrows were opposite, energy reports of the papers read at the annual meeting, held at Naples was leaving it. Mr. Maycock, he said, had recently published in August, and of the regular meetings held since till the end a simple rule for finding the direction of magnetic force due to a of the year, and of the discussions which followed. Among current of known direction in a wire. Grasp the wire with the the more noteworthy papers may be mentioned the following :- right hand, the thumb pointing in the direction of the current; On a new carpellary theory, by Signor F. Pasquale, who main- the fingers will then encircle the wire in the direction of the tains that the carpel is not derived, as has been generally sup- magnetic force. Dr. Fleming's well-known rule for induced posed, from the modification of a single leaf, but from the currents was also a right-hand rule, but as it referred to the concrescence of two, or sometimes of three leaves, which unite direction of currents, another rule was necessary when conin the formation and nutrition of the ovules and seeds.--On the sidering motors. By making the rule refer to E.M.F.'s, only Aoral structure and process of pollination in some species of one rule was required for generators and motors. For alter. Nigella, by Dr. A. Terracciano. –On the period of formation nating currents the author found it convenient to draw polar of the inflorescence within the bud of the vine, by Signor U. curves analogous to Zeuner's valve diagrams. Suppose a line Martelli.—On the non-sexual propagation of Cynomorium OP (Fig. 1), representing the maximum value of an E.M.F. or coccineum, by the same writer, who has established its parasitism on Atriplex nummularia.-Prof. G. Arcangeli also describes the
B results of experiments on the cultivation of this plant, which he finds to be parasitic on many hosts.-On earthquakes and vege. tation, by Signor A. Goiran. He finds the effects of seismic motions in the earth to be the more rapid germination of seeds, as well as a more rapid growth of the young plant.--Signor E. Tansani has a paper on the teaching of botany in gymnasia, which he considers to be in a very backward state in Italy.
The Botanical Gazette for January contains two interesting original papers :-Herr A. F. Foerste speaks of the relationship of autumn- to spring-blossoming plants, and concludes that late autumn-flowering plants may be divided into two classes—those which have developed from summer-flowering plants by the increase in the number of internodes with their appendages
D and the gradual retardation of growth, and those which have developed from spring-blossoming plants by the premature development of buds destined to flower during the ensuing current whose magnitude is a sine function of the time, spring.-Mr. H. L. Russell discourses on the effect of me- to revolve at uniform velocity about o; the intercepts chanical movement on the growth of certain plants. The oq, oq', &c., cut off by circles OQB, OQ'D, will represent the experiments were made chiefly on certain yeast-fungi ; and the magnitudes at the times corresponding to the positions oP and general results were that the development of filaments was op. The effect of lag can also be represented in such diagrams. hindered by shaking ; but that strong agitation greatly increases In cases where the variables are not sine functions, the curves the activity of cell-division, while it diminishes the intensity of OQB and oQ'D are no longer circles. Polar diagrams representfermentation. This may be compared with the fact mentioned ing the E.M.F. and current curves obtained by Prof. Ryan in his above relative to the effect of earthquakes on the growth of transformer experiments were exhibited, and a working diagram, plants.
illustrating the changes in three-phase currents, was shown. To The greater part of the number of the Nuovo Giornale show the directions of induced E.M.F.'s in diagrams of dynaBotanico Italiano for January is occupied by a paper by Signor
mos and motors, diagonal shading of the pole-faces was someA. Jatta, on the Lichens of Italy, accompanied by a very ela
times convenient ; the lines over north poles being drawn from borate bibliography. --Signor C. Massolongo has a note on a
left to right downwards in the direction of the middle stroke of floral monstrosity in Jasminum grandiflorum ; and Dr. R.
the letter N, and those over south poles from left to right upCobelli a paper on the movemenis of the Aower and fruit of wards. A conductor passing over a north pole from ”left to Erodium gruinum. These movements belong to three organs, right would have an E.M.F. induced in a downward direction, the calyx, the upper portion of the style, and the mericarp-and
as indicated by the slope of the diagonal lines. This method of do not appear to be in any way connected with the pollination representation was used to show the ways of connecting up of the flower, since the species is apparently self-fertilized, and multipolar drum armatures, the winding being supposed cut no pollinating insects were observed at any time upon it.
along a generating line, unwrapped from the core, and laid out flat in the manner adopted by Fritsche. In connection with
armatures, the author said a formula had been published by SOCIETIES AND ACADEMIES.
means of which the nature of a winding consisting of a given
number of convolutions, and to be used with a given number of LONDON.
poles, could be predetermined. This, he thought, would be Physical Society, February 26.-Prof. W. E. Ayrton, very useful in practice. Mr. Blakesley said the old method of F.R.S., Past President, in the chair.— Prof. S. P. Thompson, representing alternate current magnitudes by means of the proF.R.S., read a paper on modes of representing electromotive jections of revolving lines, seemed preferable, for it left no forces and currents in diagrams. The author said he had found ambiguity as to the directions of the quantities. The method of it advantageous in some cases to depart from the usual methods shading the poles also required that the direction in wbich the of representation, and he now brought the subject before the diagram was to be viewed should be known belore the direction Society in order to have it discussed and improvements sug- of the E.M.F. could be determined. Mr. Swinburne suggested gested. To indicate the directions of currents in wires seen that the author might use a bow to represent E.M.F., and end-on, Mr. Swinburne had used circles with and without an arrow for current. He was glad to see that Prof. Thompcrosses, but no symbol had been suggested for wires not con- son recognized the differences in dynamos and motors, veying currents. He (Prof. Thompson) thought the plain and approved of the view that mnemonic rules should reser circle should be used for inactive wires. A circle with a dot in to E.M.F. and not to current. The diagrams of drum the middle could then be used to indicate that a current was windings would be very useful, and he hoped the author flowing towards the observer, and a circle with a cross in it to would make the subject clear to ordirary workmen in represent a wire conveying a current away. These meanings the next edition of “ Dynamo-Electric Machinery.” Prof. could be recalled by considering the direction indicated by an Perry considered it undesirable to use polar curves for anyarrow, the dot showing the tip of the arrow, and the cross the thing but circles. In his opinion it was not sufficiently feathers. Some method of distinguishing between E.M.F. and known that any curve can be split up into a series of sine curves, current was required. For this he proposed to use thin-stemmed and each component dealt with separately; the separate results arrows with feathers for E.M.F.'s, and thick-stemmed ones being added together in the end. Mr. Swinburne pointed out without tails for currents. In the case of electrical transmission that before one could analyze a curve in this way, the curve of energy, this convention had the important advantage that must be known, and would probably have to be determined ex