360

But it is only the lateral filaments that are exposed to friction-this retards their motion; and the particles of the fluid, or the adjacent filaments which do not touch the pipe by their adhesion to those which do touch it, experience also a retardation, although in a less degree.

The retardation of each particle of the fluid being inversely proportional to its distance from the side of the pipe.

Hence in pipes of small diameters, whose positions are nearly horizontal, the retardation of the fluid occasioned by friction is more than equivalent to the acceleration of gravity; and the fluid is consequently deprived of motion. And although the formulæ give in the last case a velocity of one-third of an inch per second, I much doubt whether or not the water would run at all; as it must experience a considerable retardation from the effects of capillary attraction in pipes of such small diameters.

P.S. The above queries may be more readily solved by the tables given in the " Encyclopedia Britannica," vol. xx. pages 652 and 653; in which work I beg to correct the following errata: viz.

Vol. xx. page 654, col. 1, line 41, for log. 2-49472, read 2.48472. By correcting the subsequent part of the computation, the velocity comes out 19-925, instead of 20-08 inches per second; and the discharge 223-54, in.stead of 228-8 Scotch pints.

J. U.

N.B. The inquiry, I think, is not properly defined, as it is not expressed whether the end of the pipe at the reservoir is placed level with the surface of the water contained therein, or whether it is to be placed 30 feet below the surface of the water in the reservoir; in which case the pipe would be perfectly horizontal in its whole length; which, I think, is not intended, although so expressed in the inquiry.

TEMPERANCE SOCIETY.

The celebrated Dr. Doyle has addressed a letter to the Rev. G. W. Carr, Secretary to a Temperance Society formed at New Ross: from the following passage to which, it will be seen that while he cordially approves of the object which such societies have in view, he agrees with us in thinking that it is only by providing the people with a cheap and wholesome malt beverage, that they will ever be weaned, in any considerable numbers, from that excessive use of ardent spirits, which is at present so fertile a source of crime and misery.

"But the great, the insurmountable obstacle to the progress of Temperance Societies, and to all the efforts which you and I, and such as we can make, to stop the torrent of drunkenness, is found in the revenue laws. Could we but induce the Chancellor of the Exchequer to become a member of our society, and to square his budget by our rules, I have no doubt whatever but we should succeed in removing this pestilence of drunkenness out of the land. To eradicate the use of ardent spirits out of a country having such a climate as ours, and from among such a people as ours, is quite impossible; but to diminish the use of ardent spirits to the one-fifteenth part of its present amount, is, in my opinion, perfectly practicable. But as it would be as easy to stop the mouths of the Euphrates, as to stop the mouths of those who now drink whiskey in Ireland, they cannot be reclaimed until a better beverage than whiskey is provided for them at even a lower expense. All this could be done by the Chancellor of the Exchequer, if he found it more necessary to promote good morals than to secure a large revenue. I am tolerably well acquainted with the making of malt and the brewing of beer, and I have no hesitation in stating, that if malting and brewing were exempted from tax, and the impost on whiskey raised, drunkenness in a little time would almost disappear from the country."

Sir, I do not recollect any information that I have acquired from the "Mechanics' Magazine" that engaged my attention more forcibly, than the sketch of Mr. Drury's improved method of producing the sound of a bell, as given by Mr. Wm. Baddeley, jun. in your 331st No. of the "Mechanics' Magazine;" a subject entirely new to my mind. I earnestly hope that so important an improvement will not be suffered to expire in diagrams and theory. The whole scheme is so practically illustrated by Mr. W. B. jun., that if any thing be done successfully, it must, I think, be upon the principles advanced by Mr. Drury, so far, at least, as relates to the immoveable fixture of the bell; and the producing sound, by the motion of the hammer, or tongue of the bell. The perfecting of the invention by scientific means, I must, of necessity, leave to persons qualified; and would only humbly beg leave to suggest as a subject for their opinions-whether the improvement might not be put in practice on bells as they already hang. Why not strike the interior surface of the bell, as hitherto (see fig. 1.)? Or even make

use of its present tongue (see fig. 2.)? The S. suggests a stay to the tongue of the bell, that it may not strike that side. The rest of the scheme coincides with the methods (or some such as those) of Mr. Drury's. The proper construction and applications must depend on local circumstances; and the scientific calculations of such as are capable of bringing so excellent a contrivance into actual operation. I only hope some more efficient pen and pencil may have superseded this slight suggestion, which I only offer, to preserve the scheme from sinking, and to excite the ingenuity of mechanics in the construction of what may be requisite to accomplish this improved method of ringing a peal of bells. As for the improvement that may be still wanting in the formation of bells, let it not prevent this capital thought of Mr. Drury's from being applied to bells, as they are at present. Let the bell-founder and the architect lay their heads together, for the more perfect making, firing, and ringing bells, consonant with the safety of their towers. I am, Sir, yours, &c.

C. H.

362

FRENCH AND ENGLISH NAUTICAL

ALMANACS.

We have just received the Connaissance des Tems, or French Nautical Almanac, for 1832. We are glad to learn from it, that the French Board of Longitude do not so pertinaciously resist all hints for improvement, as the late English Board of Longitude did; and, comparing little things with great-the ants with the elephants of the almanac tribe-as the managers of the British Almanac have done.

The French Board announce various improvements, some of which will be introduced in the Connaissance des Tems for 1833, others in that for 1835. Among the first, we are very glad to find specified "the angular distances of Venus, Mars, Jupiter, and Saturn, respectively, from the moon," after the manner in our Nautical Almanac of the distances of certain fixed stars from the moon, at intervals of three hours. It is a curious fact, in the history of attempts to prevent the promotion of science, that Professor Schumacher, of Altona, (one of the first astronomers, and one of the most public-spirited men in Europe,) got these distances of the planets from the moon accurately computed for every three hours in an entire year (about eight or nine years ago), offered them gratuitously to the English Board of Longitude, and said he would engage to supply them annually, free of expense-simply requiring a certain, and not a large number of the printed copies, to circulate amongst Danish and German astronomers, and naval menbut that THIS LIBERAL OFFER WAS POSITIVELY DECLINED! Mr. Schumacher, therefore, published them separately; and the East India Company, and some other public bodies, have procured copies regularly from Altona, year after year.

We rejoice to hail the improvements in the Connaissance des Tems; and trust that, ere long, we shall have to congratulate Messrs. South, Baily, and others, who have struggled nobly to accomplish so desirable an object, on the appearance of similar improvements in our own Nautical Almanac.

ON THE FORM AND ACTION OF THE TEETH OF WHEELS,

Sir,-As the most eminent authors are not free from errors, and compilers or book-makers copy from authors and from each other, thereby propagating but your correspondents ought themsuch errors, it cannot be questioned selves to understand the subjects on which they may think proper to offer remarks. Indeed, nothing is more certain than that those who square their ideas entirely by what they read, without any judgment of their own, are by no means fit persons to assume the office of censurers. "S. Y. (a Young Engineer)," No. 332, p. 304, presuming on what he has seen in print, asserts that my remarks on the acting of the teeth of wheels are not such as might have been expected from one who pretends to treat the subject scientifically; and that "the best mode of forming the teeth of wheels is by involutes of circles:" and in support of his assertion, he refers your readers to Gregory's Mechanics, Robison's Mechanical Philosophy, Ency. Brit. and Rees' Cyclopedia. But although the epithet he gives himself of "young" may plead an excuse for the want of knowledge, it is certain that such want but ill accords with the title of "engineer." He tells us that the teeth of wheels working three inches deep, only slide on each other one-sixtieth of an inch; but he does not show us by what magic this is effected.

Now, as it is much better to be guided by strict matter of fact than merely by what any author whatever may happen to advance, there is no necessity for me to consult the authors he refers to-there being no difficulty in proving that the true form of the teeth of wheels are epicycloids, and consequently not involutes of circles; and that they rub or slide more or less against each other the whole depth they work into each other-the curved part of the teeth of one wheel sliding against the straight part of those of the other, the point of contact changing continually in both.

It would be decmed futile to make any remark on the wearing of the teeth, seeing that it is the obvious con sequence of their sliding against each