minds, and employs their limbs; this interest will grow up with them, and may, by degrees supplant that hatred for trees, which it is said subsists in Ireland.

Knitting and spinning are totally unfit and unprofitable for boys, weaving is a healthful exercise if not followed with too much assiduity; the flax mills now establishing in Ireland will soon supply materials every where. Is it to be supposed that the legislature will refuse to supply looins?

The boys should not work more than three hours a day. Looms for cotton and woollen goods should of course be employed in some places, instead of those for weaving narrow sacking and coarse cloth.

Stocking weaving instead of knitting should be introduced; netting and weaving sash-cord, curtain line, and fringe for furniture, might be tried. Basket making is a good employment; shoe-making is already taught, and it may be more generally introduced, for shoes are every day becoming more common in Ireland. The hours for play are not sufficient; ball-playing, gough, and cricket, and all many sports, should be encouraged: "Mens sana, in corpore sano" is the description of a useful citizen. A book should be kept, stating pri vately the genius, merits, faults and progress of every boy in every school : from each a certain number should be selected every year. And different schools should be established, either upon the present, or upon a new foundation, to breed boys to different occupations; servants, shoemakers, cabinet-makers, clerks, mer chants, surveyors, schoolmasters, parish clerks and choristers, and soldiers, who must soon from their acquire ments become serjeants, and might then by their education be brought forward in society. It was thus that the Jesuits made their pupils superior to those in any other seminary on the Continent. "Fus est et ab hoste doceri."

In all cases the work boy and his master should have part of the profit of their industry; and surely the master should be encouraged to look forward, as he grows old, to a perma. nent establishment for life.

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Consolidation of Schools....Upon the whole, the greatest improvement that could be made in these schools, would be to reduce their number, four schools containing from six to seven hundred, according to local circumstances, would answer all the ends proposed by the present diffused establishments. The superintendance of these schools would be easy and effectual.

That discipline by which armies are governed, which cannot take place in the management of a few boys, might be introduced amongst numbers; the division into small bodies, with the system of gradual subordination, and promotion from merit, would induce habits of submission and emulation, which would be carried from the school into every situation where the boys might afterwards be placed.

It would be practicable to send a master in relation to these schools for a fortnight twice a year, to teach various useful parts of knowledge, some of which are before-mentioned. From the impression made by incidental instruction, the bent of each boy's disposition might be learned, and his proper destination might be ascertained. A useful and cheap apparatus might be had for this purpose, and a proper master be found, who should not aim at teaching more than what is obviously useful. Were this effected, Protestant apprentices would soon be in such high request, as to make it an object of competition amongst the parents of the poor to have their children admitted into charter schools, and then by degrees the foolish prejudice against this mode of education would be eradicated, a circumstance which might in itself be of very high advantage to Ireland. (Signed) RICHARD L. EDGEWORTH. November, 8, 1808.

the Magazine for October, by M.D. C. as a by-stander, I shall beg leave to make some observations on them all.

From the close similarity or rather identity of the stile used by M. D. C. with that of the paper to which it refers in the Magazine for June, I am strongly inclined to believe them both the production of the same pen; since the same obscurity of expres sion noticed by Mechanicus, evidently characterizes both; but if the former was obscure, the latter is *overed with "darkness visible.*" It is also remarkable that the paper of M. D. C. is dated Dublin, October, 7. only six days after the publication of the Magazine, in which Mechanicus appeared; therefore, allowing two days for postage, only four days remain for all the experiments, made as it appears, on purpose to refute Mechanicus; these are suspicious circumstances. But being unwilling to believe that Mr. R. would have the vanity to bedaub himself with such aukward compliments, as the paper of M. D. C. contains, I shall for the present, consider the author as a distinct personage, and totally unconnected with Mr. R.

It is scarcely necessary to observe that the glass stem of a hydrometer one-fiftieth of an inch in diameter, and twelve inches long, would not bear to be loaded with weights. To

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*To give all the examples, would be to transcribe the whole paper; "let one suffice. "But I am also of a decided opinion that this does not apply, that a new discovery is made, &c." But as this may have been a mistake of the printer, in putting the word apply instead of imply, let us try another sample. "Every buoyant body, will carry or bear the weight of the water removed by the body." loaded ship is certainly a buoyant body, will it carry the weight of the water displaced? if so it must carry a weight equal to that of the whole ship and cargo, in addition to its former load! If the author meant to say that, the weight of every buoyant body, is at all times equal to the weight of the router displaced by that body ;---but the weights and bulks of both are never equal, except at the point of total immersion; this would have been strictly true; but it is not true that a buoyant body, will carry a weight that sinks it.

observe method, therefore, and reserving the most important points, between the Disputants to be last settled, I shall pass over the first part of M. D. C's paper, which is to be considered afterwards, and begin with that part where he says; The Rhapsody made use of by Mechanicus prevents me from following him any farther, to make room for a few observations of my own. Are they then not all his own observations; if not whose are they? was the writer conscious of assuming a feigned cha. racter, and thus inadvertently endeavours to conceal it? With respect to the word, rhapsody, the public, are the proper judges, to whose productions it is most applicable.

Mechanicus has said, that if the adjustment of the quantities of air and water, in the small bulb of the water barometer was made above the temperature of 424 degrees, the same adjustment would not answer below that degree, and M. D. C. acknowledges that he tried it only between the temperatures of 55 and 70, this looks very like giving up the point. He says that after repeated trials of sinking and swimming, he made a stem that answered his expectations, but carefully conceals the size of it. He complains that there are two troublesoine guests, in the shape of difficulties, that haunt him, and that he cannot dismiss, for he says they "remain with him" still.

One is,

how to adapt a scale to the glass stem, so as to correspond with a mercurial barometer. This appears a little in. consistent with an assertion in a former part of the same paper, where he say's "that many of the most ac. curate hydrometers have no figures marked on their steins," and since this is confessedly a hydrometer with the name changed, and a small air bulb added to the large bulb. How can a scale be necessary in the one case and not in the other? or if necessary for a barometer, though not for a hydrometer, how can it be difficult to adapt a scale to an instrument that shows the minute barometrical changes, more visibly than any instrument the inventor had ever seen?" Again, How could these minute barometrical changes have

been observed, since it is confessed that no scale has yet been adapted to the glass stem? these are all questions, which M. D. C. will find it difficult to answer.

The last difficulty is to get air to preserve the same proportion, and not diminish in bulk. M D. C. appears a little unreasonable to expect both these conditions, since one of them might suffice. He will find it troublesome to obtain even one of them; if so, it amounts to an admission of the objection made by Mechanicus, viz. "that air, which has been long confined under water loses its elasticity, either from part of it being decomposed, or mixing with that contained in the water." M. D. C. says "I would mention the proportions i have already found, and the kind of air I used, but I hope that Mr. R. will give some more information, being thankful for his hints already given; and I think much better of this water barometer, than as a visionary toy." What! are all the encomiums bestowed on these contrivances ended in "something better than a visionary toy?" This conclusion is no bad specimen of the anticlimax. I am ready to admit more than M. D. C. for I think the machine, not a visionary but a real toy, composed of air, water, and glass, and which would make an excellent substitute for a rattle to grown up infants.

All the minor points being disposed of, come we now to the most important point for the Disputants; for although it is certainly very uninterest ing to the public, to know whether a glass balloon filied with air, her. metically sealed, and placed on the top of a hydrometer stem is sensible to the changes of the atmosphere or not: because an instrument having the three properties of the hydrometer, thermometer and barometer, blended together, has already been proved by Mechanicus to be totally useless. But since the subject admits of demonstration, and since Mechanicus has been accused by M. D. C. of want of candour, it is but fair, to examine both sides of the question.

It was asserted by Mr. R. that an air balloon, placed on the top of a hydrometer stem, did sensibly rise

and fall with the changes of the atmosphere, or he used words to that effect; Mechanicus says the thing is impossible. Suspecting that the word impossible, may have been used in a manner too unqualified; in order to satisfy myself, I made the experiments hereafter to be related.

It must certainly be admitted, that in order to float on the top of a hydrometer stem, it is not necessary that the balloon should be light enough to float in air; yet I strongly suspected that without this condition, it would not admit of being made large enough to displace a volume of air sufficient to render even the greatest changes of the atmosphere sensible, and were this practicable it would then be beyond all measure too large and too heavy, to be placed on the top of a hydrometer stem.

The general principle must also be admitted, that if any two bodies of different specific gravities, are balanced against each other in any me dium, the specific gravity of which shall afterwards be changed, the two bodies will then lose their equilibrium (this is what M. D. C. calls by way of its title, the old and well known fact, otherwise Mr. R's datum) from this principle it results that, strictly and mathematically speaking, a ship with sails and rigging, will float higher on the water in a dense, than in a rare atmosphere. A pound of feathers balanced against a pound of gold, will vary in weight as the density of the atmosphere varies. But an air pump (could such be procured large enough) would be required to make those effects sensible, as well in those two cases, as that mentioned by M. D. C. yet no one ever thought of converting a ship, or a bunch of feathers into a barometer.

But to come nearer the point in dispute; is it not a little remarkable that neither Mr. R. nor his friend M.D.C. has ever told the size of the air balloons they used; the latter had indeed mentioned three ounces as the supposed weight, but this must be out of all proportion to the given size, and consequent weight (about two ounces) of the hydrometer bulb, on the stem of which it was placed, let the weight be supposed one ounce, and its size

three fourths of that of the hydrometer bulb; and even these proportions wil be found much too large to admit of its upright position. The dimensions of the air balloon will then be three cubic inches. The weight of a cubic foot, or 1728 cubic inches, is 1.2oz. or 1576 grains Troy weight, 1728 divided by 576, gives a quotient of three cubic inches to each grain, the balloon will therefore displace three cubic inches of air, the weight of which is one grain. Suppose now that such a change of the atmosphere took place as would cause the mer cury in a common barometer to rise or fall half an inch at once (which would be a very extraordinary case) this in round numbers is the 6th part of the whole column of mercury which is equal in weight to a column of air, the same size of the bore of the barometer tube, and the height of the whole atmosphere.-The specific gravity of the balloon would in this case be changed the 60th part of one grain. Now in order to be convinced, whether the 60th part of a grain could have any sensible effect on a hydrometer stem circumstanced as above, I procured one of Dycas's improved bydrometers which does not exceed in weight 17 penny weights, and the size of its bulb 1.62 cubic inches, consequently easier affected than one of three times its size and weight.

I immerged the hydrometer in clean water which had stood an hour in the same room, lest its temperature should have changed while the experiment was making-1 loaded the hydrometer till one of the division lines just appeared above the surface of the water, and no more.-i then took a slip of thin writing paper about six inches long and one fifth of an inch broad, with its edges cut exactly parallel, and balanced it very exactly

top of the stem, with a pair of tweezers; I placed on six of them in this manner, without perceiving the smallest alteration in the height of the stem, although the six pieces correspond to a change of three inches of mercury in a common barometer, and equal to its greatest range in this country. I afterwards placed on in the same manner all the 15 pieces (one quarter of a grain) and it was not till then that the stem was observed to sink the breadth of the division line, about the 60th part of an inch, although these 15 parts are equal to a change of 7 inches of mercury.

Let this air balloon barometer which is capable of showing the changes on only three cubic inches of air, be compared with a common barometer, which contains 14 ounces 8 pennyweights of mercury, which at the rate of 1.2oz. to a cubic foot, balances, 12 cubic feet or 20736 cubic inches of atmospheric air; and consequently shows the changes on that quantity. 20736 divided by three gives a quotient of 6912, the advantage therefore which a common barometer possesses over the bauble in question. is no less than 6912 to one; supposing its changes could possibly be rendered sensible.

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1 am happy in applauding the zeal, and even approving of the partiality avowed by the editor, in favour of any original communications which have an apparent tendency to im prove philosophy or the arts; but as silly conceits, or exploded contrivances, may be offered to public notice under the name of new or useful discoveries, an editor may with the greatest propriety submit such communications to a free and candid investigation, in order thereby to discover their several merits, or demerits.

High-street, Belfast, Dec. 5,1809.

For the Belfast Monthly Magazine.

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