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rence will be, that th section on the line a smaller scale; this principa the depth of the plane; the b adjusting it is, first to move th point of the right angle as far as go to the right, then slide the tube the lower part of the right angle int sects the line an at the bottom; this wil be found to be the most convenient. The reason of the result of the foregoing arrangment is as follows:-The motion of the slide s s producing an equal angular motion in both parts of the right angle, the angle made by the upper part with the line a t, will always be equal to the angle made by the lower part with the line a g. For example, let the centre of the right angle be moved to b, a b, representing the first interval of time, and the upper part of the right angle will make with the line a t, the angle at b, a b being the tangent, and the angle a b x being equal to the angle at b, and the radius a b, being equal to the radius a t; the tangent on the line an, will be also equal. On moving the centre to c the second interval of time, the upper angle will be increased to a tc, a c being the tangent which is double that of a b, and as the angle a c y is equal to the angle a t c, the tangent of the former angle with an equal radius would be double also; but in addition to this, the radius a c is double that of a t, therefore the tangent on the line a n, is equal 2 x 2 or 4 times that of a x. Again, on moving the centre to d, the upper angle will be a t å, a d being the tangent which is now three times that of a b, and as the angle a d z, is equal to the angle a td, the tangent of the former angle with an equal radius would be treble also, but the radius a d being equal to three times that of a t, the tangent a z, will be equal to the square, or nine times that of a x.

stands opposite the given intervals of time; for ample, to division inarked b, which may represent any given interval and the lower part of the right angle will intersect the line a n, in x; a x representing the space fallen through in that interval of time. Again, on moving the slider S, till the angular point of the right angle coincides with the division marked c, and the lower part of the right angle will intersect the line a n, in y; dy, representing the whole space fallen through at the end of the second equal interval of time, which is equal to the square of two or four times the space a x. If the angular point be now moved to d, the point of intersection on the line an, will be z; az being the whole space fallen through at the end of the third equal interval of time, being equal to the square of three or nine times the space a x and so on. And if the angular point of the right angle be moved on with an uniform velocity over the space representing the progress of time, the point of intersection will move downwards on the line a n, with accelerated velocity, exactly corresponding with the accelerated motion in the descent of falling bodies. To represent the space that any body would fall through if moving with an uniform velocity equal to that which it may have acquired at the end of any given interval of time, slide the slip s s, till the angular point of the right angle coincides with the given interval of time, and the point of intersection on the line a n, will as before represent the space fallen through; now detach the tube t from the slider, and fasten the right angle by tightening the screw at the angular point, which will prevent it from having any angular motion, (thereby preventing any acceleration,) then slide the angular point till it coincides with the succeeding interval of time, and the space between the two last points of intersection (of the lower part of the right angle) on the line an, will represent the space fallen through with the uniform velocity given; and if the last interval of time be equal to the former, it will be found that the body will fall through twice the space with the uniform velocity that it had acquired at the end of the first interval of time, (with accelerated velocity) which exactly agrees with the laws regulating the descent of falling bodies. If the tube t be placed

Fig. 2, shews the application of the same principle to the drawing of the curve of the parabola. Two sides of the plane are placed in a frame which projects above the surface; on the frame are fixed two narrow slips a b d, leaving a space underneath for the parallelogram Pppp to slide in; the paper on which the curve is to be drawn, is placed on the parallelogram; on the slip dis placed the

theler with the tube t; the sliding slip s s sh placed exactly under d, sliding in the wo grooves g g; the length of the slip s double that of the width of the plane, the right angle being attached to the middle of it in the same manner as in fig. 1; to the middle of the slip underneath is attached the small arm m, carrying the tracing point or pencil which is placed a little above the centre; the lower part of the right angle is fixed on the upper part, in such a manner that the line forming the lower edge may pass exactly over the centre of motion, as it is also continued beyond the centre, being now in the form of a T square, that the curve may be traced at one operation. To trace the curve of a parabola of any given focus, slide the tube t till the distance from a is equal to four times the focal distance; then slide the slip s s which will carry the tracing point or pencil with it, and the lower part of the T square pressing on the projecting piece at the lower part of the parallelogram, forces it downwards to those distances which are exactly in proportion to the squares of the distances of the pencil from the middle of the parallelogram, (which are exactly equal to the ordinates); therefore, the curve traced by the pencil will be that of an inverted parabola.

In the above arrangement, it is not absolutely necessary that the pencil should be exactly in the centre of the T square, or even in the middle of the sliding slip s s; the curve drawn would still be that of a parabola; if it were placed at the end of the sliding slip s s, it would trace one side only of the parabola. When the lower part of the T square makes an angle with the axis of the curve less than 45 degrees, it will not readily push the parallelogram downwards; in this case move the parallelogram downwards by the hand, at the same time keeping the lower part of the T square in contact with the projecting piece by pressing slightly against it, by which means the curve may be easily traced. The lower part of the projecting piece is cut away (see fig. 3,) to allow the upper part of it to pass over the edge of the slip s s, and to come in direct contact with the centre of the T square, when the lower part of it is in a position parallel to the line s s.

AERIAL NAVIGATION.

Sir,-Eighteen months ago, Mr. Baddeley created no small sensation by the announcement in your pages, that he had "succeeded in contriving a balloon of an entirely new description, possessing all the requisites for efficient aerial navigation, and capable of being propelled and guided at the pleasure of the aeronauts." Had some other of your correspondents vouchsafed a similar declaration, it might, in the absence of anything in the shape of a "scantling" of the invention, have been passed without much notice; but, coming from the quarter it did, the general impression was, that there must be " something in it," and, while it was regretted that" it would not be consistent with Mr. Baddeley's personal interest" to enter into particulars at that time, the period was anxiously looked forward to, at which your readers would have an opportunity of becoming acquainted with it."

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However, the readers of the Magazine have watched in vain. A year and-ahalf have since elapsed, and I do not recollect seeing a word more in relation to the matter, with the exception of a claim, in the next number, to a discovery of like nature and importance, on the part of a certain Signor Andervolti ;— who has also disappeared," and made no sign"! May I therefore be permitted to enquire, on the part of myself and the rest of the vast body of mankind who expected long ere this to have seen balloons, in the words of Mr. Baddeley,

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propelled and guided through the air with as much facility as boats at present are upon the surface of our river Thames," what are the present state and prospects of the invention in question? Whether it is intended, in the course of the summer, to start regular stage-balloons (as was to have been done in the case of the aerial ship) to "Paris, Berlin, Vienna, and other principles cities of the Continent"? Or whether, (which, is just within the verge of possibility,) the scheme has turned out to be as impracticable as the many other contrivances for the same grand purposes broached from time to time in the pages of our scientific periodicals, and has been abandoned accordingly?-Even if this be the case, Mr. Baddeley surely owes it to himself and to your readers to make the result known as widely as the original announce

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ment whose appearance raised the expectation of all so high. The world should not be any longer left in ignorance of the fate, whether good or bad, of an invention, the first rough plans of which were so satisfactory that the "scientific friends" of the author pressed themselves perfectly convinced of their feasibility, and felt satisfied that the time had arrived when balloons would cease to be scientific toys, and assume a new and useful character." This was in, or previous to the month of October 1836, yet the time has not yet arrived" for the public at large to have an opportunity of judging of the feasibility of a scheme so highly thought of, and balloons are at this present writing, just as mere "scientific toys" as ever. Is it not high time then for Mr. Baddeley to put an end to such a state of things, by publishing the details of his plan at once, or at least giving the reasons why he does not?

From some of the expressions in Mr. B.'s letter, it would seem that he contemplated taking out a patent, but as his name does not appear in any of your Lists of Patents up to the present date, it is evident that it is useless to expect any enlightenment on the subject from that quarter.

I beg to remain, Sir,
Your obedient humble servant,
PHILO-BADDELEY.

April 13, 1838.

DOMESTIC MANUFACTURE OF CIDER-NEW

CIDER-PRESS.

(From a Paper "On the Manufacture of Cider," by Mr. Towers, C.M.H.S., in the Journal of Agriculture.)

The cost of the fruit must be an ad valorem calculation; because it must depend upon circumstances which will variously affect it. I presume that an orchard exists; and, in that case, the price will be little more than that of the labour bestowed in gathering it. The preparation of the fruit is readily submitted to calculation; provided there be a cider-press in the neighbourhood; but I shall give an estimate of the expenses incurred in that part of Berkshire where I reside, as, by it, persons at a distance may not only form an idea of the extreme cheapness of this beverage, but may be induced to introduce presses in the neighbourhood, where none are, as yet, to be found.

The writers whom I have consulted, agree in their censures of the awkward machinery which is in general employed; and I can add my testimony to the justness of their remarks, from having observed the construction of the ponderous presses that still exist in Somersetshire. These are lent out on hire, and reqnire a waggon to remove them from place to place. Instead of encumbering the pages of the journal with any further account of them, I will attempt cursorily to describe a very compact and useful press, which I have seen at a village not remote from Windsor. It is kept by a gentleman for the express purpose of pressing apples for any one who will send them to him. Those who wish to make a certain quantity of cider, may have the fruit pressed, at the cost of twopence for every gallon of juice, at an hour's notice. My first experi

ment in this county was made in November 1835. I had 14 bushels of apples to spare ; these were taken six miles in sacks with the barrels for receiving the juice. In a few hours, the juice was returned to me, with a charge of six shillings for 36 gallons, a surplus quantity remaining at the mill which the barrels would not contain.

This mill or press consists of two parts. The first is a sort of case or box firmly fixed to the floor of a barn; but it would stand in any commom shed or outhouse, as it is little more than a yard long and two feet wide. There is at the top a wooden hopper to contain the apples; below that are two pair of cylindrical rollers which have an involute action in opposite directions, one towards the other; the upper pair are of wood full of iron nails or pegs, which rend and tear the apples to fragments, and deliver them to the lower pair of cylinders, made of stone. They are about 9-inches wide and 18-inches long, placed very near to each other.

The mill is set in motion by two winches, fixed to two heavy and broad fly-wheels which are turned by two men. The fragments of apples are carried by the tearingrollers, and delivered at the upper surfaces of the pressing stone cylinders; which, partaking of the same simultaneous motion, crush them to a complete pulp, and deliver that into a trough at the bottom of the case or box. Such is the tremendous power of the rollers, that the pips of the apples are completely smashed; and yet there is no appearance of effort, and scarcely any noise : nothing can be more compact or convenient.

The Pomace (as the pulp is termed) is now put into horse-hair bags and placed on the stage of the press. This apparatus consists of a square case or frame about four feet wide, which rests upon the floor. The sides of the case are made of boards eight or nine

inches wide; the bottom is of very thick and strong plank, and upon this the hair-bags are placed. A similar board of great substance is put over the bags, and this is forced by the action of two extremely powerful iron screws upon the bags The pressure is first made by the hand, one man being employed at each screw, which he turns till juice ceases to flow.

The shorter of two small levers is next passed through two of the handles of the screw, and thus an additional power is obtained. Finally, a longer lever is applied, and thus the pulp is deprived of nearly the whole of its juice. This simple and commodious press, that occupies the room of a moderately-sized table only, is capable of acting upon the pulp of 10 bushels of apples; and as each bushel of good fruit is supposed to yield three gallons of juice, 30 gallons may be obtained in a very few minutes.

WHISHAW'S HYDRAULIC TELEGRAPH. The uses of telegraphs in England have hitherto been exceedingly limited, from various causes, but more especially from the circumstance of the time of working them being very circumscribed, either from the total absence of light, or from hazy or foggy weather. The hydraulic telegraph is entirely free from such objections; and on account of its simplicity and certainty is especially calculated for the speedy transmission of intelligence, whether for purposes of state, commerce, &c.

The operation of telegraphing by this machine is so simple, as to require no extraordinary abilities on the part of the Manipulator; for, merely by regulating the increase or decrease of the column of water, by means of the cocks, it is either elevated or depressed ad libitum in the glass tubes at the different stations at the same time, to any figure of the vertical scale required.

The combination of this system are infinite; though, for ordinary purposes, a dictionary of 12,000 words is sufficient. Each word in the dictionary is represented by a corresponding figure; so that the Manipulator at one station has merely to telegraph the figures given to him, while the Manipulator at the other end returns each figure, as a proof of having the communication correct, and finds their meaning either by a reference to a general dictionary, or a dictionary for a particular purpose,-as for shipping, railways, elections. &c. These communications also may be carried on quite privately, if desirable, each telegraphic correspondent having his own set of figures.

Communications also may be made, through this medium, in different languages; as between Germany and Spain,— -a German and Spanish dictionary having similar numbers opposite corresponding words.

A great advantage of using figures is, that the longest words in the English language, many of which have from eight to twelve letters, are represented by four figures at most. The telegraph, on this principle, fixed at the Royal Gallery of Practical Science, is to full size, including the pipes, &c. Any one, therefore, may judge for himself of its great simplicity, and of the expense of fixing the whole apparatus to any

extent.

To guard against frost, it is proposed to lay the pipes four feet below the surface of the ground; and in passing over bridges the pipes would be fixed by collars in pipes.. of larger bore, and thus prevent congelation by the intervention of a non-conducting medium.

The estimated cost of a telegraph on this principle is as follows :—

1760 × 2=3520 yards of pipe in each mile, for two columns, at 8d. a yard.....

Laying down pipes, including digging and filling in, per mile

£117 6 0

80 0 0 £197 6 0

In London or other towns I have calculated the cost at double the above rate, from the greater difficulties which present themselves; viz. 4007. per mile, including the apparatus at the stations.

The most proper routes to lay down pipes in, are railways, towing-paths of canals, turnpike-roads, and occasionally, if convenient, footways across fields.

It is to be observed, that an alarm can be sounded from one station to another. The telegraph at the Royal Gallery of Practical Science is fitted up on this principle.

It has been offered to the Admiralty, to which establishment it would be of immense use in passing the London fogs, which for weeks together impede the progress of communication beyond Chelsea by the common semaphore.

As a means of communicating between the different government offices, situated in different parts of the metropolis, it would be of great use. For purposes of state, in communicating between the government departments in London and the temporary residence of the court; for giving alarms of fires to engine-stations in any part of London; for sending communications from the offices of dock companies in London to their large commercial establishments eastward for collecting the metropolitan police

in any quarter of the town at a few minutes' notice; and for a variety of other purposes, the hydraulic telegraph is eminently calculated.

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CAMUS ON THE TEETH OF WHEELS.

May, 4th 1768, died Charles Stephen Lewis Camus, the celebrated French geometrician, aged 69; author of a well known Treatise on the teeth of Wheels, in which the best forms to be given to them for the purpose of machinery, were for the first time determined, on true mathematical principles. An English translation of this treatise appeared in 1806, with some additions from the translator's own pen, which evinced an unfortunate ignorance of the scope of M. Camus's demonstrations; and have been a fruitful source of error in English mechanical practice. Camus proved clearly that the epicycloidal part of a tooth, designed to act on another wheel or pinion, ought to be generated by a circle equal to the radius of the wheel or pinion with which it is to be engaged; while his English translator represented his meaning to be, that it should be equal to the diameter ! Mr. J. I. Hawkins, who has lately favoured the public with a more correct edition of the trea

tise, states, that " many of our first-rate engine manufacturers" have been so misled by this mis-conception of the original translator of Camus, that they are daily " pouring into the market multitudes of cast-iron wheels and pinions, of various magnitudes, for cotton and other machinery, with teeth formed from the epicycloid of the diameter, instead of the radius of the opposite wheel, or pinion ;" and which must, in consequenca,

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wear out in a few years, instead of lasting the greater part of a century,- -as many of them would do, if the teeth were formed on the true principles. We regret to learn, from the same authority, that there are many wheel-makers who follow no rule of proportion at all in their formation.

"In

Lancashire, they make the teeth of watchwheels of what is called the bay-leaf pattern; they are formed altogether by the eye of the workman, and they would stare at you for a simpleton, to hear you talk about the epicycloidal curve. These Lancashire workmen should be called bay-leaf fanciers, because they cannot be bay-leaf copiers; since it is notorious that there are not two bayleaves of the same figure. It is the opinion of Mr. Hawkins, that teeth accurately formed, either by the epicycloid or involute curve, will endure the wear of a century, with less damage than teeth, as usually made, suffer n ten years..-Mechanics' Almanac.

NOTES AND NOTICES.

Mauufacture of Salt for Dairy Purposes.-The Dutch are remarkably particular as to the proper quantity and quality of their salt, of which there are three kinds manufactured. The small salt for butter, which is somewhat smaller than the common salt made in this country, is boiled or evaporated in 24 hours. This kind is also used, as already mentioned, in mixing in some districts with the Kanter cheese. The second salt is evaporated by a slower process, in about three days; it is used in salting by outward application, the Edam, Gouda, and in some places, the Kanter cheeses. This kind is beautifully formed in the natural crystals of about half an inch square. The third kind is larger sized; the crystals are nearly an inch square, and the evaporation process lasts four or five days. It is sometimes used for salting the cheeses by outward application, but principally for curing fish, beef, pork, &c. The Dutch pay great attention to the exact quantity of the particular kind of salt necessary, so that we never find the cheeses made in Holland salted to an intolerable degree, as we sometimes experience in this country. I (says Mr. Mitchell) endeavoured to discover the mode of manufacture, and learned some particulars on this important subject, but there appeared to be some secret in the process, which the manufacturers were unwilling to disclose. One thing is certain, that the use of the Dutch salt is one of the causes of the sweet and delicious flavour of their butter, which, although always well flavoured, hardly tastes of salt, or rather of that acrid quality which the poisonous bittern of the muriate and sulphate of magnesia pervading our common salt imparts to our butter; and this is very obvious in comparing the Dutch butter with the best salted butter of this country. When it is considered that the health and prosperity of the people are materially concerned in the use of this article in so many various ways, the propriety, or rather necessity, of improvement in its manufacture will be more evident, and it is rather remarkable that whilst chemistry has now advanced to such perfection, no change has taken place in the mode of making salt for several centuries. The late scientific Earl of Dundonald, the late Dr. Coventry, and the Rev. James Headrick, proposed important improvements in the mode of manufacture of this article, which, however, seem never to have been adopted.-Times.

Machinery in Ireland.-On Tuesday the 6th ultimo, the Knight of Kerry gave a grand dinner to 200 of his quarrymen, at Valencia. Their homely substantial repast consisted of the best beef, pork, and bread, with excellent ale from Murphy's brewery at Killarney, crowned with abundance of whisky punch. One hundred and fifty of their wives and daughters joined the dance in the evening, and the festivity lasted till a late hour, when all departed satisfied and happy, without one instance of drunkenness or impropriety. The feast was to celebrate the establishment of a steam-engine and machinery for dressing the fine slate-stone of the Valencia quarries, which, by enlarging the demand for material, will have the effect of increasing considerably the number of quarrymen. It is a gratifying thing to have in our country a successful enterprise, giving employinent to so large a number of fine industrious fellows, supporting their families in comfort. This is the true remedy for destitution in Ireland, and not poor-house jails. The Knight presided at the dinner, which was attended by several neighbouring clergy, Protestant and Catholic, and the repast afforded a most joyous scene of festivity and sound harmony.-Kerry Evening Post.[The machinery above referred to is, we understand, that patented by our ingenious countryman, Mr. James Hunter, superintendent of Mr. Lindsay Car-" negie's pavement quarries in Forfashire.]-Scots

man.

Society for the Promotion of Practical Design.A society under this title has just been set on foot

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