82 PHILOSOPHICAL TRANSACTIONS. [aNNO 1736. 



A Solar Eclipse observed at Rome, May 3, 1734, N.S. By the Abbh de 

 Revilus, F. R. S. and Andr. Celcius, F. R. S. N° 442, p. 294. 



True time. 

 At lO*^ 22"" 35% A. M. The eclipse had begun a Utile. 

 ] ] 5 O , The greatest obscuration 2 digits. 

 11 51 O, The end of the eclipse. 



The Description and Manner of using an Instrument for measuring the Degrees 

 of the Expansion of Melals by Heal. By Mr. John Ellicott. N°443, p. 297. 



AA, (fig. 6, pi. 4) represents a flat plate of brass, which, for more strength, 

 is screwed down to a thick piece of mahogany : on this plate are screwed three 

 pieces of brass, two of which, marked bb, serve as supports for the flat iron 

 bar c ; and which, on account of its use, is called the standard bar. The upper 

 part of the third piece of brass is a circle, about 3 inches diameter, divided into 

 360 equal parts or degrees : within this circle is a moveable plate, divided like- 

 wise into 360 parts, and a small steel index. The brass circle in the figure is 

 marked d, and the moveable plate d. On the standard bar is laid the bar of 

 metal e, on which the experiment is to be made, as e. 



F is a lever, 24- inches in length, fastened to an axis, which turns in two 

 pieces of brass, screwed to one of the supports, marked b : to the end of this 

 lever is fastened a chain, or silk line, which, after being wound round a small 

 cylinder, to which the index in the brass circle d is fastened, passes over a 

 pulley, and has a weight hung to the end of it : on the axis, to which the 

 lever is fixed, is a pulley, 4- of an inch diameter, to which a piece of watch- 

 chain is fastened ; the other end of this chain is hooked to a strong spring, 

 marked g, and bearing against one end of the metal e. 



H is a lever, exactly of the same form and dimensions with the former ; but 

 the chain fastened to the pulley on its axis, is hooked to the standard bar.* The 

 line fastened to the end of this lever, after being wound round a cylinder, to 

 which the moveable plate is fixed, passes over a small pulley, and has a weight 

 hung to the end of it ; or rather the same line passing under a pulley, to which 

 the weight is hung, has its other end fastened to the lever f : thus one weight 

 serves for both levers, as in the figure. 



From this description it is plain, that whenever the bar e is lengthened, it 

 gives liberty to the weight to draw the lever f upwards by its action on the 



• N. B. The chain to the former pulley being fastened to a spring, and not directly to the metal «, 

 is only for the more easy shifting the metals. 



