V2+2g S sin. iV2+2gh, the same as in my last article. When I wrote my last article, I had not read Dr. Lardner's correction of some part of his evidence on the Great Western Railway Bill. He states in his correction, vol. xxiv. p. 67, "We must add to the square of the velocity due to the descent down the plane from a state of rest the square of the initial velocity, &c." Dr. Lardner does not explain how we are to find the velocity due to the descent from a state of rest The question he alludes to is this:-The length of the Boxhill plane is 2 miles, or 13,200 feet, the descent 1 in 107. Now, suppose a carriage or train to have acquired a velocity of 20 miles per hour on commencing the descent, the steam being then turned off, Dr. Lardner states, that the velocity at the foot of the plane will be 50 miles per hour. We shall see how this, agrees with the theorem, v = √ V2 + 2 g S sin. i. Dr. Lardner assumes a descent of 1 in 250 as a balance for friction. Now, suppose 250 a, 107 b, and let A premium of ten guineas, by Sir Charles Lemon, Bart., and R. W. Fox, Esq., for the best series of practical experiments, tending to prove how the dangers attendant on the present mode of blasting rocks may be most effectually and economically guarded against. Two premiums, the first of seven guineas, the second of three guineas, by G. S. Borlase, Esq., for the two best chemical or mechanical plans for ventilating mines, which can be applied to the Cornish mines with advantage. A premium of ten guineas, by G. C. Fox, Esq., for the best essay on the various diseases incidental to miners, their causes, and the best practical means of remedying them. Any statistical information as to their longevity, compared with that of the other population of the county, will be deemed highly desirable. A premium of ten pounds, by John Hearle Tremayne, Esq., for the best available method, or improvement on the plans already suggested, for facilitating the ascent and descent of miners, provided the judges shall 'consider it to possess sufficient merit to entitle it to such premium. A premium of ten guineas, by E. W. W. Pendarves, Esq., for the best practical method of ascertaining the quantity of water raised by each lift of pumps in the mines of this county. Two premiums, the first of seven guineas, If I should be called upon to demonstrate some of the steps of the above calculation, I will willingly do so. the second of three guineas, by John Taylor, Esq., for the most complete and accurate accounts of the quantity of water supplied to the boilers, the number of bushels of coals consumed, and the duty performed by any engine, for a period of not less than six months in the ensuing year. A premium of ten pounds, by the Rev. Canon Rogers, for the most economical, safe, and efficient plan for lighting mines, consistent with the health of the miner,-such plan to be accompanied by a statement of the present actual consumption of candles, and the cost per dozen lbs., at some of the prin cipal Cornish mines. INDIAN INK. Sir, In the 611th Number of the Mechanics' Magazine, you notice a method of making Indian.ink by mixing lampblack with jelly. I had been endeavouring to find a solvent for charcoal, and I found that, by mixing it with a little milk (the charcoal being ground to an impalpable powder) just enough to wet it, you could obtain Indian-ink. Tue same process may be employed with lamp-black. If the presence of milk be an objection, it is easily got quit of by adding a large quantity of water, then allowing the charcoal to precipitate, and afterwards pouring off the water; which operation may be repeated till all the milk is abstracted. I am, &c. HENRICUS. AUSTEN'S STEAM-ENGINE. We quoted in No. 641, from the Falmouth Packet, a brief notice of the extraordinary results of an experimental trial made at the Fowey Consols and Lanescot Mines, with a new steam-engine invented by a Mr. Austen. Since then we have been favoured by a correspondent at St. Austel with the following copy of the official Report on the subject, and also with some notes upon it, which are well deserving of attention.-ED. M. M. Experimental Trial of Austen's SteamEngine, of 80-inches Cylinder, at the Fowey Consols and Lanescot Mines, Oct. 22d and 23d, 1835. This celebrated engine, from its extraordinary and unprecedented power and astonishing rate of duty, having caused several engineers and others to express doubts respecting the truth of the reports, as published by Mr. Lean, in his monthly lists the engineers, Mr. William Petherick and Mr. William West, at the suggestion of some scientific gentlemen of the county, and with the sanction and authority of the adventurers of those mines, have subjected her to a public trial. A public meeting for that purpose took place at the above mines, at noon, on Thursday, the 22d inst., when J. S. Enys, Esq., of Enys, was requested by the meeting to nominate competent persons, totally unconnected with the mines, as a Committee, for the purpose of conducting the examination, in conformity with the general usage on such occasions. 1 The following persons were then appointed for that purpose: Mr. SAMUEL LYLE, Mr. WILLIAM REMFRY, Mr. JOSEPH MORCOM, Jun. Who undertook the duty, and made the following Report: REPORT. We, the undersigned, having been appointed a Committee to conduct the trial of Austen's Engine, make the following Report of our proceedings, and the result of the experiment. Statement of Proceedings. 1st. The coal-sheds carefully examined and found to be quite empty. 2d. Twenty-eight bushels of coals measured in the presence of the Committee and others. 3d. A bushel of coals weighed, and found to be 94lbs. 4th. The coal-shed door immediately locked, the key kept by the Committee, and the door sealed. 5th. The Committee's Counter at starting registered 00,000,660, and Mr. Lean, the Reporter's counter, 02,187,480. The counters locked and sealed as soon as their state was ascertained, and the keys delivered to the Chairman of the Committee. 6th. Quantity of grease delivered for the consumption of the engine 12lbs., and oil 1 quart. 7th. State of the fires strictly examined. 8th. Water in the boilers found to be at the regular working gauge. 9th. Steam gauge at starting 36. 10th. Stroke in the shaft 9 feet 3 inches. The trial commenced on Thursday, at 28 minutes after 1 o'clock, P.M. During the trial, which lasted 24 hours and 27 minutes, the steam-gauge fluctuated between 36 and 45, showing a pressure of from 36 to 45lbs. on every square inch of the boilers; and the length of stroke in the shaft ranged from 9 feet 3 inches to 9 feet 5 inches, but the duty has been calculated at the minimum of 9 feet 3 inches. The exact quantity of coals consumed was twenty-four bushels. On unlocking and unsealing the counters in the presence of every member of the Committee, their respective states were found to be as follow, viz.: Committee's counter registered 6,947 counter, registered .......21,937,67 Showing that the engine made 6,287 strokes, which is found to be 429 strokes per minute. The working of the lilly lift was suspended, in consequence of the prang of the bucket breaking, and this lift remained idle from 40 minutes past 7 o'clock in the evening, to 23 minutes past 10 o'clock at night, being 2 hours and 43 minutes, for which stoppage, 3 hours has been allowed in the calculation of duty. The steam-gauge at the termination of the trial stood at 44, being 7 more than at the beginning. The water in the boilers was higher at the conclusion than at the commencement of the experiment. (Signed) JOHN BUDGE, Chairman. THOMAS PETHERICK, JOHN BRAY, JAMES THOMAS, WILLIAM REMFRY, JOSEPH MORCOM, Jun. Pitmen appointed by the Committee for examining the Pump Work. JOHN PASCOE, from Herland Mines. Notes. The Report of the Committee of Pitmen was to the effect, that all the lifts were solid. During the stoppage of the lilly lift the water from the puppy lift ran to waste, and the tye, rose, and crown, were supplied with schammal water from different levels. As a faster velocity than three strokes per minute was advantageous to the engine, the water had been allowed to accumulate in the mine, and also to keep the lifts solid; the lilly lift, therefore, was evidently a lifting pump. The greater quantity of the water is usually raised by plungers, on the outdoor or return stroke. The injection water was about 50° Fahr.; the water from the condensers between 80° and 90o. The duty is made up in the mode introduced by James Watt, namely, by valuing the one-third savings of coal due to him under his patent right, which is still the fair proportional test of the work performed by engines. All the engines in the county are employed in pumping work high expansively, from 4 to 10 times, using steam in the boilers from 25 to 50lbs. per square inch on the safety-valve, or 39 to 64 lbs. per square inch pressure. Previous to its entry into the condensers, it is reduced by expansion to 4 or 10lbs. under atmospheric pressure. The mean pressure on the piston often exceeds Bolton and Watt's practice, as the load on the piston from the weight of main rods, &c. (sometimes 270 fathoms), varies from 7 to 17lbs. per square inch.-See Lean's Report. The load in the shaft of an 80 varies from 50,000lbs. to 108,000 lbs.-See Trelawny's engine-wheel, Vor. Annexed is an extract from one of the monthly Reports of Mr. Lean, alluded to in the introduction to the preceding Report:— CONSTRUCTION OF CHIMNEYS. Sir,-Having been obliged by the insertion of my proposed plans for quickly putting out fires, &c. in No. 632, Mechanics' Magazine, I beg leave to hand you the plan I would recommend for building chimneys, combining the following advantages; viz. simplicity, good draft, great safety, and means of cleansing at any time in a few minutes by any person-the operation affecting the whole of the connecting flues at once; my grand object being to remedy effectually that great evil and national disgrace-the cleansing of chimneys by children. I would carry up from the cellar or lowest apartment a straight, cylindrical chimney, 12 inches in diameter, to about a foot above the ridge of the house-top, upon which any ornamental cap might be placed. A bar of iron, an inch thick, should be placed across, on the top course of bricks with cement, and another to correspond 2 feet from the bottom. In the centre of each of these bars an iron grooved revolving-wheel, about 1 inch thick by 4 inches diameter, should be fixed. A chain should be passed round these wheels, the ends being firmly united by a piece of iron, one-fourth of an inch thick and 4 inches square. To this iron plate fix the brush by two thumb-screws. The brush is made thus:-A circular piece of elm, 4 or 5 inches thick and 7 inches in diameter, is thickly armed on its circumference with strong bristles or whalebone, 3 inches long out of the wood. A hole is made in the centre of the brush 4 inches in diameter, the inner surface being lined with sheet-iron. Through this hole the double chain passes, the thumb-screws being firmly screwed to the brush. A proper handle being put on the lower wheel, will thus enable the whole length of the chimney to be cleansed effectually in a few minutes, by the brush passing upwards, and down again by reversing the motion of the handle. Three feet from the bottom of the chimney there should be a door, to remain open except when sweeping. The fire-places being all parallel with each other, should have an opening about 6 inches in diameter passing off chimney; and as this would never exceed 18 or 20 inches in length, it could when necessary be swept with a handbrush. There would by this plan be a to the great saving of room; and there might be more if the chimney were built in the party-wall, which would be perfectly safe, and admit of two sets of fire-places, probably 8 or 10 in number; by this means there would only be a 9-inch projection into the room, with a solid mantel-piece over. If the chimney is by the side of the fire-place, there must be a corresponding thickness of brick-work on the other side for uniformity sake. I at first contemplated further improvement, but cannot at present see the way clearly for arranging it. It is this:-I wished to make in the side of this blank part a capacious opening, 18 inches above the level, narrowing gradually and sloping to the bottom of the grate, with a wellfitted door to the upper orifice. My view then was, to put one or two bushels of coals into this place; but the difficulty is, the means of propelling it forward for supply to the bottom of the fire. The advantages of this part of the plan would be a supply for four or five days, thereby saving trouble in drawing-rooms, &c.; and also, that as the carburetted hydrogen formed at the bottom of the fire rises, it would be completely consumed, and, consequently, only a small quantity of smoke would pass to the chimney. Your obedient servant, G. L. SMART. Enfield, Nov. 5, 1835. AERIAL NAVIGATION BY BIRDS. Sir,-Perceiving in your present volume allusion made by Mr. T. M. Mackintosh to the practicability of training up certain species of the winged tribe for the purpose of aerial navigation, I beg the favour of a corner in your Magazine to offer a few remarks upon the subject. I perfectly agree with the writer that original projectors are too often thought visionary, and turned into ridicule, when they are induced to lay before the public whatever appears extraordinary and difficult of accomplishment. It so happens, that the idea of using birds for aerial navigation is a very old and favourite one of mine; and I have only neglected endeavours to bring it into actual practice, through the want of leisure to accomplish a task, requiring, it is true, little ingenuity, but much persevering assiduity and patience. From the supposition that an idea of the sort would only be laughed at, I have hitherto only ventured to mention it to a few friends, with my opinion, that perhaps all the ancient accounts of flying may not be so fabulous as we now suppose them. However, as your correspondent has boldly broken the ice upon the subject, he may be pleased to know that his idea is not entirely solitary, notwithstanding the little variation there may be in our notions upon it; for my ideas exceed his in what may be judged extravagance, believing that eagles possess collectively sufficient power to fly with a man even without the buoyant aid of a balloon; and nothing but the failure of an ably conducted, practical experiment, could satisfy my mind that they could not be trained up to accomplish it. The following, I think, would be all the mechanical skill required, unless experience directed other measures : To a kind of very light or open wickerwork I would attach about 30 eagles, in rows one above the other, and about 3 abreast, supposing them capable of flying with a weight of 180 lbs., at the rate of 6 lbs. each, being the supposed weight of the man, together with the car and wickerwork. The aeronaut should be so placed in his car in the interior of the wickerwork, as that the latter containing the lower tier of eagles should, upon a descent, take the ground first. For the guidance of the machine many methods may be imagined, three of which I will mention. The best would be to train up an eagle as a leader, with a light rein to direct him; if that was impracticable, I should fix a piece of meat at the end of a long, light pole, fitted to the fore part of the car, and working upon an universal joint, with a short arm from the fulcrum for the aeronaut to alter the position of the meat in every direction, which the birds should be trained up to follow. If the above and every other plan failed to give the eagles a voluntary direction, I would then resort to a coercive one, by a long pole, working on an universal joint (or an equivalent action), projected abaft the car with fan-tails at its extremity, and at right angles with each other, horizontally and vertically, so as to direct the machine in every direction in the simplest and easiest manner. To realise a desideratum of this nature it requires, first of all, a person of property, and who would devote his whole |