stands a saw-mill, which cuts an immense quantity of timber. The owners, as well as several of the workmen who attend the mill, state it as a fact that at night, in the course of a given time, with the same head or quantity of water, and without any alteration being made in the gearing, or machinery of the mill, the saw cuts much more timber, than it does in the same time in day-light; and further, that it cuts more in a given time in winter than it does in summer. The owners, from being accustomed to the motion and tone of the saw in the course of the day, say they can readily perceive an increase of strokes and a greater force in the saw, at night; but how to account for it they know not. It has become a matter of much speculation and dispute among the mechanics, workmen, and floaters of lumber on the Susquehannah.—A gentleman, who deals largely in lumber, and who sometimes attends to the floating of

rafts himself, states, that a raft will float nearly a third faster in the night, than in the day. The two facts are probably referable to the same cause; and the discovery of that cause is desirable.

SAMUEL WAGNER.

REMARK.

No other explanation of the facts stated above occurs than that which is implied in the title given to this fragment. It would be interesting to know, whether other persons have noticed the same facts, and whether the mills have been observed to move more slowly as the water approaches the freezing point, which ought to be the fact, as between 40° and 32° water grows lighter, although growing colder, according to a remarkable, but now well established exception in the case of this fluid.-Ed. Am. Journ.

Washerwomen say that the temper of the wearer has a great effect upon the shirt in cleansing. Is there any truth in the assertion ?-V.

Observe the new moon through a silk

napkin, and the number of moons visible will denote her age in days. This holds good till she is five or six days old. What is the cause of this phenomenon?-V.

Remarkable height of the Barometer.— The Barometer at Worcester lately stood at the extraordinary height of 30 inches 96-100ths, a point of elevation exceeding by 6-100ths, any observation made in that neighbourhood, for many years past. This fact is the more remarkable, as there was not that dryness in the air which usually accompanies this state of the mercury.

Hatching of Fish.-The Chinese have a method of hatching the spawn of fish, and thus protecting it from those accidents which ordinarily destroy so large a portion of it. The fishermen collect with care, on the

margin and surface of waters, all those gelatinous masses which contain the spawn of fish; after they have found a sufficient quantity, they fill with it the shell of a fresh hen's egg, which they have previously emptied, stop up the hole, and put it under a setting fowl. At the expiration of a certain number of days, they break the shell in water warmed by the sun: the young fry are presently hatched, and are kept in pure fresh water till they are large enough to be thrown into the pond with the old fish. The sale of spawn for this purpose, forms an important branch of trade in China.

CURLL, PRINTER.

THE following curious fact we copy from The Chemist,' No. 45, for 15th January last. We have often observed it ourselves. If the water is warm, and a spoonful of rum be placed gently on the water, so as to swim on the top, the appearance will be more distinct, and an extraordinary ebullition will appear in the centre of the tumbler.

"Take a large goblet (the larger the better), and having filled it twothirds with water, produce a tone from it, by rubbing the hand previously wetted (or a rosined bow) on the outside of the rim, in the manner the musical glasses are played; with this difference, that you confine the friction as much as possible to one point until the tone is produced. Four points only of the circle of the glass will become agitated, and these of equal distances from each other; which points may be distinctly seen by observing the rimpling they make on the surface of the water, as in fig. 1. If the

tone or note be now raised to a fifth from the first, which may easily be done after a little practice, six points in the sides of the glass will become agitated, indicating that six portions of the circle are in motion: see fig. 2. If now you raise the tone to the octave, eight points of agitation will be distinctly seen. When the vibrations combine in odd numbers, they give five radii, as in fig. 3.

A large bell-glass, supported steadily on a foot, is more easily made to produce these different tones by the wet hand than a common goblet, and the rimpling on the surface of the water will be more defined and distinct.

These little experiments show a certain accordance in very different things; or rather we should say, in different parts of the kingdom of nature. It is somewhat remarkable, that the tones which are to the ear harmony,' should also cause those definite and regular forms which are beauty to the eye."

6

DESCRIPTION OF A NEW OF A WASTER SLUICE. The Lever Sluice, Figure 4. THIS apparatus, when placed on a reservoir that supplies any canal, mill, or other work with water, (where the aqueduct between the reservoir and such work is on a level,) will always open of its own accord, and let down the quantity of water wanted by such work and no more; so that it not only supersedes a waterman, but also saves a great deal of water.

Fig. 4, A, B, is a tunnel through which the water passes from the reservoir to

B, C, the aqueduct that carries the water to the mills.

B, D, a float that rises and falls with the water in the aqueduct. A, an aperture in the mouth of the tunnel.

E, the self-acting sluice that opens and shuts that aperture.

F, G, a lever which turns upon the fulcrum H, and is connected at one end with sluice E, and at the other with the float B, D.

The sluice E, is here represented open, (as when the mills are going,) but when the water is stopped at the mills, it rises in the aqueduct, and with it the float B, D, which raises the end G, and lowers the end, F, of the lever F, G, and shuts

the sluice E. When the water is again let upon the wheel at the mills, the surface of the aqueduct falls, and with it the float, which opens the sluice E, as before.

Upon the lever F, G, there is another small lever K, L, which turns upon the fulcrum L, and has a weight M, suspended to the other end K. In the ordinary working of the apparatus this lever is quite stationary, and produces no effect whatever; but during floods, the aqueduct is swelled by streams that run into it between the reservoir and the mills, and when this happens when the mills are not at work, the water, rising in the aqueduct, presses up the float upon one end of the lever when the other can get no farther down, and would thereby strain or break the apparatus; but by this contrivance this extra pressure merely pushes up the small lever K, L, without straining any other part. Of course, the weight M, is so adjusted, that the lever K, L, will not at any time move till the sluice is shut, but upon the least extra pressure after it shuts, the lever will rise.

The dimensions of the float are nineteen feet square by seven inches deep; the lever is twenty-seven feet long, being twice the length between the fulcrum and the sluice that it is between the fulcrum and the float. The sluice is three feet three inches long, and fifteen inches deep.

To determine the dimenproper sions of the float, and relative lengths of the ends of the lever, it was necessary to ascertain how far the sluice required to be raised to pass the quantity of water wanted, and also how far the water in the aqueduct might be raised above the level absolutely necessary for supplying the works; the first was found to be seven inches, and the last only four inches. The end of

the lever connected with the float was made therefore only half the length of the end connected with the sluice; and the float was made of such dimensions, that when sunk half an inch in water, the weight of water thereby displaced was equal to twice the weight required to shut the sluice.* When, therefore, the water in the aqueduct rises upon the float half an inch, (besides what it sinks by its own weight,) the sluice begins to move; and by the time the water rises other three inches and a half, the sluice is of course seven inches down, or shut.

This apparatus was erected at Rothsay in 1816.

The Waster Sluice, Figure 5.

This sluice, when placed upon any river, canal, reservoir, or collection of water, prevents the water within the embankment from rising above the height we choose to assign to it; for whenever it rises to that height the sluice opens and passes the extra water; and, whenever that extra water is passed, it shuts again; so that whilst it saves the banks at all times from damage

To

*Twice the weight, because here the lever is two to one against the float. ascertain the power required to open or shut the sluice, (which is easily done by a lever and weights,) it must be tried when the water in the reservoir is at the highest, which, in this case, is seven feet To asabove the bottom of the sluice. certain how far the sluice must be raised to pass the necessary supply, it must be tried when the water in the reservoir is nearly at the lowest, and in this instance was done when it stood three feet above the bottom of the sluice. The quantity of water required is equal to about the power of fifty horses, the fall at the wheel being twenty feet. The aqueduct is about seven hundred yards long, twelve feet wide, three deep, and its bottom about twelve inches lower than the bottomof the sluice.

by overflow, it never wastes any water we wish to retain.

A, C, B, L, is part of a canal, river, stream, or collection of water.

B, C, high-water-mark, or the greatest height to which the water is to be allowed to rise.

B, D, a sluice, or folding dam, which turns on pivots at D.

E, F, a hollow cylinder, having a small aperture in its bottom, to which is joined

E, L, a small pipe always open. I, I, I, I, small holes in the cylinder E, F, on the line of highwater-mark.

G, H, another cylinder, waterproof, that moves up and down freely within the cylinder E, F; and the weight of which keeps the sluice B, D, shut by its connection with

B, K, H, a chain fixed to the cylinder G, H, at H, thence passing over the pulley K, has its other end fixed to the sluice B, D, at B.

When the water in the canal, river, or pond, rises to the line B, C, it passes into the cylinder E, F, at the small holes I, I, I, I; and this lessens the weight of cylinder G, H, so much, that the pressure of the water in front of sluice B, D, throws it open. When the

water subsides, so as not to enter these holes, the cylinder is emptied by the tube E, L, and then the weight of the cylinder G, H, shuts the sluice as before. The dimensions and weight of this cylinder must of course correspond with the weight of the column of water pressing upon the sluice B, D. An apparatus of this kind was first erected at Rothsay in 1817. The dimensions of one of these are:cylinder G, H, two feet diameter, and two feet deep over all; weight 500 lbs.* Cylinder E, F, five feet

This weight is considerably more than necessary when the sluice is placed

ten inches deep, two feet one inch diameter inside: sluice B, D, four feet long and two feet deep.

This sluice is here represented with the pivots on which it turns at its under edge, but they may be placed either at the upper or under edge, as circumstances render advisable. The upper edge is also here represented on a level with high-water-mark, but, if necessary, it may be placed any where between that and the bottom of the pond or aqueduct, or right below, as on an aqueduct bridge, or similar situation. The cylinders may also be placed on the outside of the dam or embankment, by having a pipe to communicate between them and the water within; but in whatever situation the sluice or cylinders may be placed, the pipe that communicates between the cylinders and the water within the embankment must

always have its opening there exactly at the level of high-water-mark, or at the greatest height to which the water therein is to be permitted to rise.

with the pivots at its under, and the chain at its upper, edge; but it was calculated to be powerful enough when the sluice was turned with the pivots at its upper and the chain at its under edge, to which position it has since been changed.

Although the cylinder G, H, requires to be heavier to shut the sluice when its pivots are at the top, yet, to pass the same quantity of water, it does not require to move half so far as when they are at the bottom, and therefore the cylinder E, F, may be made much shorter; so that the cost in either case is nearly the same, or rather in favour of the pivots being at the top. In most cases this last position is preferable; there are instances, however, in which the other is more advisable, such as in a river where wood, ice, or other bulky substances may be expected to float occasionally on the surface; but such cases require a particular construction adapted to the circumstances.