the manner of managing the eggs when they are there. Each oven consists of two brick buildings 9 feet high, 38 long, and 12 broad, with a kind of passage between them 3 feet wide, closed up at each end by the walls which terminate the two buildings, and arched over, forming a gallery of the same height.

The two buildings are divided by cross walls, each into 8 chambers, 9 feet high, and each chamber is again separated horizontally into two by a very flat arch, perforated in the middle with an aperture 2 feet diameter; so that each building contains two ranges of chambers 3 feet high, the upper range communicating with the lower by these apertures; the apartments, though not very commodious for the Bermeans that enter them, are very fit for supporting the degree of heat necessary to hatch the eggs, which must be nearly 32 deg. above freezing on Reaumur's thermometer.

The door to every one of these chambers, above and be low, is a round hole a foot and a half in diameter, which forms a double range of ox-eyes on either side of the gal lery; and the door of the gallery itself is a like hole, being the only entrance into the oven.

The eggs are disposed in the lower chambers, upon mats, or beds of hair or hemp, and the door which communicates from each lower chamber to the gallery, is carefully closed up with a wadding of the same matter. The fire is kindled in the upper chambers, and the smoke, which passes into the gallery through the before-mentioned apertures, escapes from thence by the holes in the arch, which are carefully closed up as soon as the oven is become hot enough and the fire is extinguished. They bern neither wood nor coals, which would make too fierce a fire, but a mixture of the dried dung of animals and straw.

From the time of putting out the fire in the oven, part of the eggs are removed into the upper chambers, which though they are now useless, as to their first office, become yet a commodious receptacle for the chickens when hatched, and suit better with the frequent visits which the Bermeans make, to turn the eggs, and carefully pick out, and take away the rotten ones; the stinking vapour of which would otherwise spoil the rest, or kill the young chickens.

The requisite time for hatching each brood in the oven, as well as under the hen, is about 21 days; but as they keep up the heat of their ovens six months together, each oven can very well produce 8 broods of about 45,000 eggs each. The Bermean, who has the management of the oven, is to furnish 30,000 chickens every brood; the other 15,000

either perish, or turn to his own profit. Every oven, therefore, produces annually to its master 240,000 chickens, and the number of these ovens being 386, the whole number of chickens, exclusive of those which are allowed to the ma pager, amounts to 92,640,000,

1755, Aug.

XVI. Absurdity of enthusiastic Predictions.

MR. URBAN,

*

IN the reign of King Henry VIII. prophecies and predic tions were in great vogue, the study of astrology being then in much esteem. Amongst other instances, one Bolton, who was Prior of St. Bartholomew, in the city of London, a person of some learning, pretended to have found out by the stars, that a mighty deluge, at such a time, would drown the city of London, and being fully persuaded himself of the truth of this, he built a house at Harrow-on-the-Hill, and storing it with provisions for a competent season, retired to it; but the event not answering the prediction, both he and his art became the public ridicule of the town. The Prior went upon a science founded on no rational principles; but an anonymous pamphlet vouches the authority of one of the greatest of our astronomers, Dr. Halley, for the return of a comet in 1758, which moving in the same line with the earth, and in the same part of the line, must necessarily set it on fire. This now is an event that concerns the whole race of mankind, even the catastrophe of this terraqueous globe, and, therefore, I am willing to treat it with all imaginable seriousness, as the author plainly designed it should.

Your correspondents, Graticola and Witchell, have shewn that the author of the pamphlet has committed a mistake, for that the comet, which according to the calculation of Dr. Halley will return A. D. 1758, is not the comet whose trajectory will coincide with the line of the earth's orbit. Moreover, that the comet expected in the year 1758, will never approach nearer the body of the earth than four millions of miles. I think it needful for you, Mr. Urban, to repeat it once more in your Magazine, that the author of the

* Speed's History, p. 1050.

pamphlet has run into this error, that so every one, into whose hands this pamphlet may fall, those especially who may have overlooked the notices of your correspondents above mentioned, may be assured of it. And this, Sir, is the more necessary, because, as it appears, many ignorant people, unskilled in the science of astronomy, and withal of timorous, or rather very fearful dispositions, have been extremely uneasy upon this account. Whereupon I cannot but observe, that authors who throw out such important particulars as these, though it be done with the best design in the world, should be very sure on their hand, before they alarm us with their notices, lest the subjecting of weak minds to groundless panics, should contribute to embitter their lives, which has something in it very cruel, and even criminal.

But since, Sir, I am embarked on this subject, I will, with your leave, add a few words more upon it. It is agreed, that this world is not eternal; that it shall some time be destroyed by fire, and possibly, but not certainly, by a comet. But whether the comet, whose return is expected, A. D. 2255, will effect it or not, I think is very uncertain. For not to mention, that the end of this world may be sooner, for ought we know, the period or year of this comet being not less than 575 solar years, an observator cannot have had experiences enow, repeated at due distances, to ascertain the return of it to a year, especially considering the irregularity which is known to attend the motion of these eccentrical bodies. Besides, the scriptures of the New Testament every where represent the final con summation of all things, as a point of knowledge entirely hidden from man, and, I presume, for the same reason as the day of our death is concealed from us; but it would no longer remain a secret, were it to depend on the known revolution of a comet. No one, therefore, ought to rely, in this weighty manner, on the calculation of the acutest astronomer, but rather reflect, on the other hand, 1st, That he knows not how soon this event may happen; and 2dly, that to him the day of his death is in effect the day of judgment, since, according to the doctrine of this Protestant church, as the tree falls so it must lie. A reflection, which if it be considered withal, to how many real disasters, without having recourse to any imaginary ones, the life of man is daily exposed, will be abundantly sufficient for the purpose of true religion, that is, to make men think on the judgment of the great day; and therefore there is no occasion to unsettle their minds by any unreasonable, and at the same time, groundless fears, which as they tend so greatly to distract

them, instead of doing them any service, are likely in the end to do them a great deal of harm.

1756, Feb.

Yours, &c.

PAUL GEMSege.

XVII. Dr. Hales's method of obtaining fresh Sea-water.

THE effect of causing an incessant shower of air to ascend through the boiling liquor in a still, to my surprise, I found to be very considerable. The method I used was by means of a flat round tin box, six inches diameter, and an inch and a half deep; which is placed at the bottom of the still on four knobs half an inch high, to make room for the liquor to spread over the whole bottom of the still. The mouth of the still being too narrow for the tin box to enter, which should be as wide as the bottom of the still, it may be divided into two parts with a hinge at one side, and a clasp at the other, to fix it together when in the still. The air pipe which passes through the head of the still, will help to keep the air-box from moving to and fro by the motion of the ship, or three or four small spurs may be fixed to the sides of the air-box, and reach to the sides of the still. The cover and sides of the air-box were punched full of very small holes, a quarter of an inch distant from each other. On the middle of the lid was fixed a nosle, aboye half an inch wide, fitted to receive, to put on, and take off the lower end of the tin pipe, which was 20 inches long, and passed through a hole in the head of the still. Four inches of the upper end of this pipe were bent gibbet-fashion, almost at right angles to the upright, in order to the uniting it with the enlarged nose of a pair of bellows, by means of a short calf-skin pipe. This tin airbox, and many more, were made by Mr. Tedway, tinman, against the Mews Gate, Charing Cross.

The double bellows were bound fast to a frame at the upper part of the iron nose, and at the lower handle, to work them more commodiously. And that the upper half of the double bellows may duly rise and fall, in order to cause a constant stream of air (besides the usual contracting spiral springs within side), several flat weights of lead must be laid on the upper part of the bellows near the handle, with a hole in their middle, to fix them on an upright iron pin, fastened on the bellows; so the weights may be commodiously put on or taken off, according to the different depths of water in

the still. Thus, if the depth of the water in the still be 12 inches from the surface of the depressed water in the airbox, then the pressure of the included air against the upper part of the bellows, will be equal to that of a body of water a foot deep, and as broad as the inner surface of that board. It will therefore be requisite to add or take off weights according to the different depths of the water in the still, at different periods of the same distillation. Where the stills are fixed in ships, the air may be conveyed to them from the bellows through a small leathern pipe, distended with spiral coils of wire, or bamboo canes, or broad small wooden pipes, like hollow fishing rods.

The quantity of water distilled in a given time by this way of continual ventilation, is, at a medium, more than double of the usual distillation. It is to be hoped, therefore, that so considerable an increase will be of great benefit to navigation, and save much fire.

By ventilation with a 20-gallon still, 240 gallons, or a ton and 24 gallons, may be distilled in 20 hours, with little more than two bushels of coals, allowing for the time of heating the still full of cold water. A ton in 24 hours will more than suffice for a 60 gun ship with 400 men, and larger may have proportionably larger stills. Ten-gallon stills will produce 120 gallons in 20 hours, and 5 gallon ones, 64 gallons.

Dr. Butler proposes pouring in more sea-water through a funnel fixed in the head of the still, when more than half has been distilled off, whereby it will soon acquire a distilling heat, adding chalk in such proportion as shall be found requisite. The funnel hole must be stopped with a cork, or small copper plate, turning on and off upon a pin.

The waste of fuel will be less in proportion in large, than in small stills, and the wider the still head is, so much the more liquor will be distilled.

It is of great importance to keep all parts of the still clean and free from rust, or verdigrease of the copper.

Now supposing, that in a 60 gun ship, the 110 tons of water for four months use, were distilled at the expense of three bushels of coals per ton, this would take 9 chaldrons, or about 13 tons weight, or 94 tons less than the 110 tons of store-water, and allowing 24 tons for the still-water casks and coals, there will be 70 tons weight of stowage saved thereby.

1756, Jan.