« AnteriorContinuar »
made that they can be opened and closed at will, because these furnish an efficient means for controlling the humidity, providing the weatherboarding of the building is tight, as it should be. In ordinary weather, it is probably better to use only the ventilating doors near the ground, and the roof ventilators, leaving the higher side doors closed, except as an emergency seems to require special ventilation, and the control may be mainly exercised by the roof ventilators, since by opening or closing these more or less, the air, as it rises between the hanging tobacco plants, may be compelled to rise more or less rapidly, as desirable. But it should be remembered, that when the external air is very moist, as in rainy
FJO. C3. TREE CRirKET ((Ecmthus nireus). The plate at right is the male, viewed from above. At the left, female, side view. •
weather, this upward current of air will largely cease, because the absorption of water from the tobacco will be greatly checked. At such times, the temperature of the air between the plants must be raised, to restore normal absorption, and the only way to do this is to provide artificial heat. Placing lighted lamps beneath the roof ventilators will help to produce an upward current of air, as was proved in our experiments, but this will not avail to prevent pole burn if the air that enters the building is already on the verge of saturation.
The curing house should be enclosed in such a manner that the amount of external air that enters it is under control, and should be provided with some kind of heating apparatus that renders it possible to reduce the humidity of the air in wet weather. To ascertain whether the air is too humid, hang a psychrometei (Fig. 57) between the plants in a central part of the barn. The wet bulb in this instrument should show a depression below the dry bulb of not less than one and one-half or more than two degrees. If the wet bulb shows a greater depression, it indicates that the air is so nearly saturated with moisture that it can no longer take up the water given off by the leaves. This is the condition that induces pole barn. Now apply artificial heat to dry the air, opening the upper ventilators to carry off the heated moist air, and the danger will be averted. Keep up the heat until the psychrometer gets back to the desired standard—wet bulb not less than one or more than two degrees below dry bulb.
From these Wisconsin experiments, the conclusion seems warrantable, that with a temperature within the curing house of not exceeding 75° F., a degree of atmospheric humidity represented by a wet bulb depression of one and one-half degrees, when the psychrometer is between the plants, and is not exposed to unusual air cur. rents, does not endanger the tobacco to pole burn, and that an occasional variation to one degree is safe, at least if not prolonged. But a wet bulb depression of less than one degree is dangerous, and it prolonged, is almost sure to result in pole burn. It will be wise to make one and one-half degrees of depression for the wet bulb the minimum, rather than one degree, not because one degree is dangerous, but because it provides too little margin between the safety and danger limits. The atmosphere throughout the curing house cannot be changed immediately by starting the fires, and if these are started as soon as the wet bulb depression becomes less than one and one-half degrees, if the weather is becoming rapidly damper, it might sometimes be difficult to prevent the atmosphere within from becoming so damp as to register less than one degree of depression for the wet bulb before the fires could prevent it.
After two seasons' trial of this, what may be called scientific, method of curing, Goff feels warranted "in commending it to the attention of all who aim to pro
ne. (A. LEAF INJURED BY RED-LEGGED GRASSHOPPER.
duce the first quality of air-cured cigar tobacco. It has the advantage of curing the crop under the best known conditions, and hence, of developing the highest possible quality. It demands a somewhat more expensive building, and a greater amount of care and intelligence than the average Wisconsin tobacco grower has been accustomed to devote to his crop. But 'what is worth doing at all is worth doing well,' and as a rule, a business will prove most profitable when conducted in the best nanner."
On a single morning during the curing season, a very perceptible odor of pole burn pervaded the building, and the wet bulb depression was considerably less than one degree. But fire was immediately started, and in twenty-four hours the ominous odor was almost entirely dispelled, while the psychrometer registered a fraction over one degree. A very slight amount of poleburned tobacco was found in the crop, but not more than is usually found in dry seasons, while the general quality, so far as the curing was concerned, was pronounced superior.
The heating apparatus for this purpose may be like that used in the Snow barn (see Fig. 43), or in the Yellow tobacco barn (Fig. 30). Another arrangement is that suggested by Goff, as shown in Fig. 58, which is especially adapted to tobacco barns now in use. It can be put in at a first cost of $25 to $v5, according to the size of the h ouse. The increased value of a single crop saved from a severe attack of pole burn by this system would more than repay the cost, and if, by being able to exclude hot and dry winds, the crop may be cured slowly in dry seasons, the apparatus may be made to pay for itself every year. We are not aware that the experiment has ever been tried in this country, but it would be feasible to provide pans, or tubs, of water on the floor of the tobacco house, which, by evaporating, would furnish the necessary humidity during a hot and dry period that otherwise might cure the tobacco too quickly. With the heating apparatus, tobacco may be hung a little closer than would otherwise be prudent, thua permitting a somewhat smaller building for a given acreage.
If a new caring home is to be provided with the heating apparatus, it would be well to build it two feet higher than the needs of the tobacco alone would require, to provide more room for the pipes beneath the lower tier. Goff thinks a curing house 100 feet long would be sufficiently warmed with four 36-inch box stoves, carrying seven-inch pipe, placed as shown in Fig. 58. The stove should be let into a little basement, bricked or stoned up beneath the sills. The pipes should start from the ground level, and rise eight or ten inches to the rod. If they come in the way of hanging tobacco, remove a sufficient number of plants to make room. They may be supported on temporary brick piers, or suspended by wires from the poles carrying the tobacco. That portion of the pipes extending outside of the building will be more durable if made of galvanized iron, and should be capped with spark arresters, but the remainder may be of common sheet iron. No difficulty is experienced in securing a good draft, and if the tobacco is not hung too thickly, the humidity of the air in a tight tobacco barn will be found to respond readily to the heat from the stoves, even where a very little fire is used. After the curing is completed, the pipes are taken down and stored for use next year.
Curing Leaf Alone vs. Curing on Stalk.—The bulk of the cigar leaf grown in the United States is cured on the stalk,—that is, the plant is cut up at the bottom, allowed to wilt, and then the entire plant is hung in the barn, as described in the chapter on cigar leaf. In Florida, however, the crop is largely harvested leaf by leaf, as described in the chapter on Florida tobacco. The cost of handling each leaf separately was about one-third higher than by the stalk system, at the Pennsylvania station, and was quite as large at the North Carolina station