498 



PHILOSOPHICAL TRANSACTIONS. 



[anno 1774. 



The year to which the several ages be- 

 low have an equal chance to live. 



compare, by this table, in the early part of life, 

 the probability that the inhabitants in Chester 

 have, to live longer than in Northampton, Nor- 

 wich, and especially much longer than in Lon- 

 don. But when they have arrived at 70 years 

 old, the chance of living, at all the places, is 

 nearly equal. It is a matter of curiosity, to 

 observe how much longer women live than men. 

 This fact is well established by former observa- 

 tions on this subject, and is confirmed by this 



register. During the last year 12 widowers have died, and 53 widows; that is 

 above 4 times the number. Between 80 and QO years old, 2 men and 1 8 women 

 have died; that is 9 times as many. Above go years old, 4 have died, and all 

 women. 



FIJ. Electrical Experiments. By Mr.Edw. Nairne, of London, Mathematical 



Instrument-maker, p. 79- 



These experiments were made with an instrument of Mr. Nairne's own work- 

 manship, a description of which is prefixed. The glass cylinder of this machine 

 was 12 inches diameter, and the cylindrical part 19 inches long, exclusive of the 

 necks; the cushion or rubber 14 inches long, and 5 inches broad, supported by 

 2 wooden springs; which springs were fixed on 2 glass rods, which lie horizontal 

 under the cylinder, and serve to insulate the cushion. The conductor to this 

 machine was 3 feet long, and 12 inches diameter; at the end of it was a short 

 brass rod, with a ball; it was supported on 2 stands, with solid glass rods or 

 pillars. The ball, for receiving the electrical spark from the conductor, was of 

 brass, and fixed to the end of a brass tube, movable in a hole in the top of the 

 receiving stand; from the bottom of this stand a chain passes along the floor, 

 till it is in contact with the chain hanging from the back of the cushion. Mr. 

 ^. with this machine has frequently drawn electrical sparks, at the distance of 

 12, 13, or 134- inches, from the prime conductor. These were indeed the dis- 

 tances, to which the electrical fire would commonly strike. It would sometimes 

 reach the distance of 14 inches; though but seldom. 



Mr. N. used also a small brass conductor, instead of the large one, for charging 

 the batteries, which batteries are composed of 4 boxes, each containing 16 jars 

 of 12 inches high and 4 inches diameter, coated 8 inches high; so that, in the 

 64 jars, there are very nearly 50 square feet of coated surface. The electro- 

 meter is raised, so as to be 4 feet from the bottom, which rests on the jars, to 

 the ball at top. Discharging this battery, through a piece of iron wire (not steel) 

 of -T-^ of an inch diameter, and 45 inches long, it flew about the room in in- 



