On the charging Capacity of coated Electrical Jars, 250 



fcross m\ and having thus removed the obstruction, the two 

 frames e efg are closed together by the springs pp> so that 

 the bars^g inclose his leg, and the clicks in the locks pre- 

 vent the bars being opened without the screws S. In some 

 of the machines which Mr. Salmon has made since the 

 model was deposited with the Society, the locks are made 

 like figure 2, L, where a common key is to be introduced, 

 and, when turned round, catches the tail of the click ; it 

 may have wards to prevent the using of a false key, though 

 ho wards are shown in the plate. Part of the screw D for 

 securing the trap from being carried away by depredators, 

 is shown on a larger scale at N, in order that the peculiar 

 form of its threads may be better seen, which fix it firmly 

 in the earth. Such - screws would be very serviceable in 

 fastening horses at grass, 8cc. 



L. An Account of a New Method of increasing the charging 

 Capacity of coated Electrical Jdrs, discovered by John 

 Wingfield, Esq. of Shrewsbury *. Communicated by 

 Mr. John Cuthbertson, Philosophical Instrument- 

 Maker ', Poland Street, Soho; iv it h some Experiments by 

 himself on that Subject. 



Ls my treatise entitled Practical Electricity and Galvanism, 

 page 103, I have said that breathing into coated electrical 

 jars increased their charging capacity to such an astonishing 

 degree, that their discharge would fuse four times the length, 

 of wire more than they could in ordinary circumstances ; 

 which I proved by experiments 147 and 155. Since that 

 publication, large electrical batteries are become more ge- 

 neral, and the number of jars increased; so that batteries 

 containing thirty, sixty, and even a hundred jars are fre- 

 quently met with; and, when so numerous, breathing inU) 

 each jar is very disagreeable; and not only that, but in very 

 dry states of the atmosphere, when most wanted, is even 

 ineffectual, as those jars first breathed into lose ihat pro- 

 perty which was produced in them by breathing, before the 

 last can have obtained it : so that various other means have 

 been tried ; such as wetting the inside of the jars, and put- 

 ting wet sponges into them, or by greasing and oiling the 

 uncoated part in the inside ; all of which gave very uncer- 

 tain results, till John Wingfield, esq. communicated to me, 



* A gentleman who has lately very much, distinguished himself, not only 

 in the electrical science, but in all other branches of experimental philo- 

 sophy. 



R 8 he 



