perior to the common methods, by the properties of numbers and converging series. The example taken by the author is log. 99, which may easily be found several ways: thus 1. 99= 1. 11+1.9=1.11+2. 1. 3=1. 10+l. (1+ič) +2. l. 3=1. 10+ 2. 1. 3+ M{ — or 10 I I 2 (10) 2+ &c. } 1.99=1.100+1.(1)=21.10+M. {1002(100)2 100) 2+ &c. } I I Description of a Machine for saving Persons from the upper Stories of a House on Fire. By Nicholas Collin, D. D., the Inventor. With a Drawing from the Model.-Whatever may be the practical efficacy of this machine, it is at least a simple one. On a broad plank moveable on wheels, suppose a hollow cylinder to be erected: in this cylinder, as a socket, another cylinder is made to move, by means of ropes fastened to windlasses, upward or downward; across the top of the last mentioned pole, or cylinder, is put a lever, with arms of unequal length: at the end of the longer arm, is swung a basket, capable of containing four persons; and from the end of the shorter arm, a rope is fastened to the plank or platform of the whole machine. From this description, the use of the contrivance may be discerned: for, if the shaft be elevated within the socket, then, in order to preserve the same distance from the plank, the end of the shorter arm of the lever must approach the shaft, or the shorter arm must descend and the longer ascend; and therefore the basket, into which persons in danger from fire are to be received, is elevated from two causes; while a reversion of the operation makes the basket descend. It appears to us, however, that there would be considerable difficulty in applying the end, to which the basket is fixed, to the window or other part of the building at which the persons in danger may be supposed to be placed, An easy and accurate Method of adjusting the Glasses of Hadley's Quadrant, on Land for the Back Observation. By Robert Patterson. The necessary apparatus, and its use, are thus briefly described: Take a piece of plane glass (a piece of looking glass will do very well)-take the polish off one side of it, and cement it, with the rough side down, on the flat side of the segment of a wooden ball. The ball may be about three or four inches in diameter, and the piece of glass of about the same dimensions. Or the glass may be cemented to a piece of board, and this board to a three or four pound shot, or small hand-granade, when either of these may be conveniently had. Next take a piece of triangular board of about four inches on the side, and through this cut a triangular mortice of about two inches inches on the side. Near the corners of this board let there be inserted three small nails, or pieces of wire, to serve as feet' for it to Stand on. " • Method of making the Adjustment, or finding the Quantity of the Index-' Error. At any time when the sun shines, set your triangular board on a table, the cill of a window, or any other convenient stand exposed to the sun, and place the ball with the piece of glass, on the triangular mortice; which, touching the ball only in three points, will consequently keep it steady in any position. Turn the ball into such a position that the plane of the glass may be, as nearly as you can judge, parallel to the equator; and then incline this plane, in the direction of the meridian passing through the sun, till the sun be about 45° above it. Now take your octant, and by the fore-obervation, bring one of the limbs of the sun's image, seen by a double reflection from the specula of the instrument, exactly into contact with the image of the same limb, seen by a single reflection from the surface of the glass plane, and read off the angle pointed out by the index. Immediately turn round your instrument, and bring the same limbs into contact by the back-observation. If the angle now pointed out by the index be exactly the supplement (to 180°) of the former angle, the horizon-glass for the back-observation will be truly adjusted, or exactly at right-angles with the horizon-glass for the fore-observation: but if these two be not equal, then take half their difference, which will be the correction or index-error for the back observation; supposing the fore horizon-glass to have been previously well adjusted.' This correction will be additive to all angles measured by the backobservation, when the angle pointed out by the index in the first of the above observations is greater than the supplement of the other, and vice versa. For the sake of greater accuracy. you may repeat these observations till you have taken two, four, or six sets; observing that if in your first set you begin with the fore-observation, as above directed, then in your second set you must begin with the back-observation, and so on. A mean of the corrections thus obtained may be taken as the true correction of adjustment.' In the conclusion of the paper, are added a few miscellaneous remarks relative to the subject. An Essay tending to improve intelligible Signals, and to discover an universal Language. From an anonymous Correspondent in France (probably the Inventor of the Telegraph). Translated from the French.-Opposite to several numbers in a constructed table, are put syllables, so that a phrase, when translated from the table, consists of a series of fractions; thus, il ne devroit 4 +3 and these pas is expressed by 5, 3 , Fractions are again to be translated by the operator at the tele R 4 graph. graph. There does not seem to us to be much ingenuity in this scheme, nor is the author very clear and explicit.-In the latter part of this short essay, he proposes the construction of an universal character, by the aid of figures. Barometrical Measurement of the Blue Ridge, Warm Spring, and Alleghany Mountains, in Virginia, taken in the Summer of the Year 1791.-Measurements by means of the barometer are uncertain but the present measurements, according to the author, are the more worthy of reliance, from the circumstance of the changes in the barometer being smaller and less frequent in Virginia than in England. By a letter of Mr. Jefferson, inserted in the memoir, it appears that this gentleman's measurement by an instrument is not materially different from that of the author. Observations made on the Old French Landing at Presqu' Isle, to determine the Latitude of the Town of Erie. In a Letter from Andrew Ellicott, to Robert Patterson, Secretary of the Society.From these observations, the latitude of the landing is 42° 8′ 17" N., and the latitude of the beginning of the town, 42° 8' 14". N. An Improvement in Boats for River Navigations. Described in a Letter to Mr. Robert Patterson. By Nicholas King. The folKing.-The lowing extract shews why the lock-navigation, so common in this country, cannot be adopted in America: The nature of the country, the rugged courses of most of the rivers, and the sudden swells they are liable to from the heavy rains, render the lock-navigation, with towing-paths along the banks of the rivers, as in Europe, in most cases impracticable, or very expensive. Nature seems here to have precluded the inhabitants from other assistance in navigating rivers, than manual labour, expensive and tedious. The difficulties attending the navigation of our rivers against the current are such as to render them much less serviceable than rivers in general are; and you are under the necessity of having the boats of great length and narrow; and of sending with them double the number of hands required to navigate them when loaded, in order to enable them to set the boat up against the current on their return. These boats are more difficult to steer and manage, in intricate and rapid parts of the rivers, on account of their length; are subject to receive damage from striking on rocks and sand-banks, and from the uneven surface and motion of the water where the descent is rapid, or the weather boisterous; and frequently get twisted and ruined when the water subsides and leaves them on the shore. Supposing that the lock-navigation, or overcoming the descent of the river by means of locks, could be generally reduced to practice, yet the length of these locks, in proportion to the tonnage of the boats, would render the expence of their construction more than the revenue arising from the tolls would warrant: but few indeed are the rivers rivers in which the navigation by locks is practicable, on account of the rapidity of the waters and violence of the freshes. Hence it follows, that notwithstanding this has hitherto been the most prevalent mode of overcoming such obstructions in rivers, it ought not to be attempted here, if better modes can be pointed out,' The plan which Mr. King proposes is to convey the boat over an inclined plane, and to compose it of four boats put together with hinges. The advantage of this contrivance is that, at the inclined plane, the boat can be taken in pieces, and the several parts conveyed over without much difficulty:-moreover, that, in descending down the river, the component boats may be separately navigated; and, in a river full of rapids, sands, and rocks, a short boat is much more commodious and manageable than a long one. The design of the author is illustrated with plates. - General Principles and Construction of a Submarine Vessel. Communicated by D. Bushnell of Connecticut, the Inventor, in a Letter of October 1787, to Thomas Jefferson, then Minister Plenipotentiary of the United States at Paris.-A few months since, the people of this country were amused, or alarmed, according to their disposition, by the project of submarine boats, which were to convey hither an army of invaders, or were to enter our harbours and blow up our ships of war. However strange or ridiculous the idea might appear, it still had some foundation; and the present paper contains the description of a small submarine boat and its apparatus, with which an attempt was actually made to blow up a ship of fifty guns. As the description of the boat, &c. is too long for us to insert, we must be contented with extracting an account of an experiment made with it: After various attempts to find an operator to my wish, I sent one who appeared more expert than the rest, from New-York, to a 50 gun ship lying not far from Governor's Island. He went under the ship, and attempted to fix the wooden screw into her bottom, but struck, as he supposes, a bar of iron, which passes from the rudder, hinge, and is spiked under the ship's quarter. Had he moved a few inches, which he might have done, without rowing, I have no doubt but he would have found wood where he might have fixed the screw; or if the ship were sheathed with copper, he might easily have pierced it: but, not being well skilled in the management of the vessel, in attempting to move to another place, he lost the ship. After seeking her in vain for some time, he rowed some distance, and rose to the surface of the water, but found day-light had advanced so far, that he durst not renew the attempt. He says that he could easily have fastened the magazine under the stem of the ship, above water, as he rowed up to the stern, and touched it before he descended. Had he fastened it there, the explosion of one hundred and fifty pounds of powder, powder, (the quantity contained in the magazine), must have been fatal to the ship. In his return from the ship to New-York, he passed near Governor's Island, and thought he was discovered by the enemy, on the island being in haste to avoid the danger he feared, he cast off the magazine, as he imagined it retarded him in the swell, which was very considerable. After the magazine had been cast off one hour, (the time the internal apparatus was set to run,) it blew up with great violence.' This vessel was completed in the year 1775, and employed. by the author against the English shipping during the contest in America. The Description of a Morld Board of the least Resistance, and of the easiest and most certain Construction. Taken from a Letter to Sir John Sinclair, President of the Board of Agriculture at London.The writer's description of the board, and of the mode. of forming it, is so minute, that it is impossible here to give an adequate notion of it; and we hesitate to pronounce on its practical usefulness. In the latter part of the memoir, the lover of peace breaks out; and this constructor of the mouldboard of a plough calculates what improvements in the Highlands of Scotland, and in the mountains of Auvergne, might have been produced by the money which has been thrown away in a single war. Thermometrical Observations made at Fort Washington, commening June 1790, and ending April 1791. By Daniel Britt and G.Turner: To which are added, for some Time, the Rise and Fall of the Ohio.-These observations are recorded in a series of tables. Calculations relating to Grist and Saw Mills, for determining the Quantity of Water necessary to produce the desired Effect when the Head and Fall are given, in order to ascertain the Dimensions of a new-invented Steam Engine, intended to give Motion to Water Wheels in Places where there is no Fall, and but a very small Stream or Spring. By John Nancarrow. - According to the author's own account, we are here furnished with a correction of Emerson's faulty expression for the velocity of water issuing from an orifice; ifs be the space fallen through, m = 16, then, from the principles of mechanics, the velocity 4ms: but, when water issues from an orifice, Emerson considers the velocity as being that which is acquired through a space equal to half of the height of the water in the vessel, and consequently puts its = √2ms: Mr. N., however, without offering his reasons, will have it = 2√ms. . Previously to the determination of the dimensions of the steam engine necessary to be used, Mr. N. examines and cal culates |