VOL. XXVII.] PHILOSOPHICAL TRANSACTIONS. ' 6l3 



535 grains, and its diameter one way measured 5^ inches, but its opposite dia- 

 meter only 5 inches. On the descent of these balls, the pendulum made only 

 one vibration more than in the other experiment ; that is, the quicksilver 

 grounded exactly at 8 vibrations, and there were g more before the other ball 

 arrived at the same place. 



These experiments were made from the top of the cupola of St. Paul's, Lon- 

 don; from whence to the floor, on which the balls were dropped, measured 

 near 220 feet. It is to be observed, that the quicksilver balls made no sensible 

 impression on the floor on which they descended^ which at that time was 

 covered with deal boards, notwithstanding their weight and the velocity of 

 descent. 

 The following experiments on the descent of bodies in air, were made in the 



same manner, at the place before-mentioned, answering very exactly with 



the former. 



Quicksilver balls. Large thin glass balls. 



Weight in Diam. Time of falling in Weight in Diam. Time of falling in 



grains. IGthsof inch. half seconds. grains. inch. lOths half seconds. 



908 8 8 5J0 5.1 17 



993 .8 8 a little less 642 5.2 16 



866 8 8 599 5.1 16 



747 7i 8 a little more 515 5.0 l6^ 



808 7i 8 . 483 5.0 17 



784 7i 8 a little more 641 5.2 16. 



These experiments were made June the 9th, 17 10; at which time the height 

 of the quicksilver in the barometer was 29.7 inches, and the thermometer 60 

 degrees above the freezing point. 



Note. — ^That the quicksilver balls, and the large thin glass balls, were dropped 

 together, as they are ranged in their several lines. 



Experiments showing the Effects of Air passed through Red-hot Metals, &c. 

 By Mr. F. Haukshee, F. R. S. N° 328, p. 199. 



To find what effect such a medium as air, passed through red-hot metals, 

 might have on the lives of animals, I contrived the following method : I took 

 a large receiver, open at top, about 4 inches diameter, which was covered with 

 a brass plate and wet leather, as usual in glasses of such a make. To this plate 

 at top, which had a screw with a small perforation, belonged a cock, from 

 which proceeded a small hollow wire, about 3 feet in length ; that end of the 

 wire farthest from the receiver was put into a hollow piece of cast brass, pretty 

 thick in substance, but the hole was not quite through ; and the hole being 



