§iS £xperi*>iefits ivItA large eleEirical Batteries. 



eaci. The fame fort of wire was not tried with this ; but it could be calculated from other 

 forts of wire which it melted, that it was capable of melting 655 inches, being alfo at the 

 rate of 1,3 inch for each fquarefoot. This increafe of power, which is almoft double that 

 of Mr. Nairne, might be attributed to the a£ting power of tlie maclune; for though Mr. 

 Nairne's machine poflijfled the (trongcfl acling power of any machine made at that time, yet 

 It could not be fuppofed to poflefs that high charging property of the Hacrlem machine. 



Since my return to London, I have made feveral batteries, commonly compofed of 15 jars, 

 each containing 168 fquarc inches of coated furface, confequently the whole battery contains 

 17 fquare feet of coating. This battery, according to tiie proportion of that made by Mr, 

 Nairne, fliould fufe 6,3 inches, and in proportion to the Haerlem batteries, it ought to fufe 

 22 inches; but inftead of following that proportion, it is found to fufe 60 Inches, which is an 

 aftonifliing increafe of force. For the battery isonlyabout one-third part of that of Mr. Nairne, 

 and fufes a much greater length of wire ; and though it is only -/^ part of that at Haerlem, 

 yet it fufes t'o of the length of wire. It feems difficult at firfl; fight to account for this advan- 

 tage. I have before remarked, that the proportional difference between the charge of the 

 battery at Haerlem and Mr. Nairne' s, might be accounted for, from the high charging power 

 of the great machine 5 but the refult of the laft-mentioned experiments overturns that notion j 

 as it can by no means be fuppofed, that a fingle 2-feet plate machine, which I have ufed to 

 charge the battery of 1 7 fquare feet fo high as to fufe 60 inches, can have a higher charging 

 poW^er tlian that at Haerlem ; fo that it mufl proceed from fome other caufe. It might be 

 queftioned whether all thebatteries were alike judicioufly conftru£led. A-s to Mr. Nairne's, it 

 had certainly faults, both with refpeft to the coating aftd the mounting of the jars ; but the 

 batteries at Haerlem were as judicioufly conftrudled as my prefent one, which I am fpeaking 

 of, and which exceeds them in fuch an aftonifliing degree in its proportional force. The only 

 difference between my prefent batteries and thefe at Haerlem is in the glafs. They were coni- 

 poifed of glafs, blown in Bohemia, and thofe which I make here are of white flint-glafs. I 

 mention this faft, but I am not inclined to think that the caufe of the difference depends on 

 the glafs, becaufe I remember to have melted the fame quantity of wire with one jar of that 

 kind of glafs when in Amfterdam, as I do at prefent with white flint-glafs ; fo that it only 

 remains now to be fought for ip the manner of ufing or charging each battery, and here we 

 fhall probably find a means of folving this paradox. 



With regard to the batteries at Haerlem, they were never attempted to be charged but in 

 dry weather, being fuch as was then commonly called favourable for eleftrical experiments. 

 TJiere was no convenience in the room where the machine and batteries were ufed, for making 

 a fire, which was therefore ill calculated for eleftrical experiments : the batteries previous to 

 charging, were made as clean and dry as poffible ; and if they received a charge fo high as to 

 caufe a fpontaneous explofion, they were then looked upon to be in their moft favourable ftate. 

 It was about thistime that we were told by Mr. Brooke, that a coated jar would take a higher 

 charge when dirty, than when clean ; but the degree of dirtynefs was fo ill defined, that 

 I muft own I never could dirty a fingle jar fo as to anfwer, or to come near what was faid of 

 it; and to pretend to bring all the jars in a large battery, containing upwards of two hundred, 

 iirto that ftate of dirtynefs was never attempted ; neither dees it appear that Mr. Brooke ever 



t}iought 



