Ekclncal hijlyuments. — ManufaSlure of Hals. 399 



The operation is this:— Let B be brought as near to A as the ccnftruaion will admit. 

 In this cafe it mufl be remarked that the wire proceeding from B will touch another wire 

 that communicates with the earth. Let eledricity be then communicated to A. The plate 

 A will receive about one hundred times as much eleftricity when B is thus applied at about 

 l-40th of an inch diftance, than it would have otherwife acquired at a like intenfity, and li 

 will poiTefs the contrary ftate nearly equal. Let B then be removed fo as to come in contad 

 with C, of which the capacity is no lefs increafed by the vicinity of D. The eledricity of 

 B will be fliared between itfelf and C in proportion to their capacities ; that is to fay, 

 about 99 parts in C, and 1 in B. At the next repetition B will bring 100 parts, which, 

 together with the 99 parts in C, will be fhared in the fame manner ; that is to fay, 197 in C, 

 and 2 in B. In this manner, without entering into the confidcration of ferles where the 

 data cannot pretend to minute accuracy, it is clear that the procefs, indefinitely prolonged, 

 can never produce a greater charge in C than 100 times the quantity conveyed at each 

 Cngle motion by B ; that is to fay, 100 X 100 times, or 10,000 times the intenfity of the 

 original oppofite ekaricity given to A, provided D be drawn back to leave C in a difen- 

 gaged ftate. 



It has always appeared to me that the doubtful refults of the doubler muft arife from the 

 natural or fpontaneous ftate of the plates A and B, at their firft conjunaion. If this charge 

 be too ftrong to be deftroyed by the energy of the communicated ekaricity, the doubler 

 niuft in the refult Ihew the fame ekaricity as it would have fliewn without fuch communi- 

 cation, though fomewhat later. And if the fame circumftancc were to obtain in the plates 

 A and B of Mr. Cavallo's laft inftrument, or any other contrivance operating by a charge, 

 I do not fee but that the refults muft be equally uncertain. If the ekarkity of H, inftcad' 

 of being accumulated in C of the multiplier, had been employed to produce the contrary 

 ftate in D, and thence by communication to A, as in tlie doubler, it does not appear that any 

 uncertainty could follow, provided only that the firft efFeft of the conjunaion of A and 

 B had been governed by the conimunicated ekaricity. And if this re.ifoning be true, it 

 will follow from that and the faas, that the uncertainty of the doubler exifts alfo in the 

 condenfer, the colkaor, the fpinning inftru:,ient, and the multiplier, though the firft-men- 

 tioned inftrument alone is delicate enough to ftiew it ; and that in all ekaricitks whicli 

 are ftrong enough to affea any of the latter, the doubler may be ufed without fear of an 

 equivocal refult. 



III. 



A Memoir on certain Methods of Economy and Improvement in the Manufaaure of Hats. 

 By Citizen ChaUSSJER *. 



X 



1. HE progrefs of the arts has been long retarded by prejudice, and the fcrvile difpofition 

 which attaches itfelf without enquiry to the ancient praaices of bufinefs ; and more particu- 

 larly by the fpirit of individual intereft and fufpicion which have prevailed among artifts, and 

 iaduced tUem to conceal their operations under a kind of myfterious veil. By this means 



* Journal Polytcclini.juc, cahicr I. j>. 160, 



tht 



