2j$ Mr. Nicholson’s Experiments and 
lifting of two plates, 33 Inches diameter, has only half the 
intenfity, though he reckons it a very good one. This machine 
is about equal in abfolute power to my 9-inch cylinder, with its 
ihort rubber; but it is near thirty times as dear in price. In 
all thefe deductions I omit the computations, for the fake of 
brevity, and becaufe they are eafily made. The data are found 
in the defcription of the Teylerian machine, and its continua- 
tion publifhed at Harlem in the years 1785 and 1787. 
I (hall here take the liberty of ohferving, that the adtion of 
the cylinder, by a Ample cufhion or the hand, which excited 
the aftonifhment of all Europe, in the memory of our co-tem- 
poraries, was firft improved by the addition of a leathern flap ; 
then by moiftening the rubber 5 afterwards by applying the 
amalgam ; and, laftly, by the addition of a filk flap. Now, I 
find, by experiment, that we at prefent obtain upwards of 
forty times the intenfity which the bare hand produces ; and 
confequently -that, fince eighteen times our prefent intenfity 
will equal the utmoft we can now con den fe on ftrong glafs 
even in the form of a charge ; we have a lefs ftep to take be- 
fore we arrive at that amazing power, than our immediate pre* 
deceffors have already made. 
My 9 *inch cylinder, when broken, proved to be p. T of ail 
inch thick. 
Sect. II. Upon the luminous Appearances of Ele&ricity and the 
Action of Points . , 
25. Some of the luminous appearances, with balls in the 
pofitive ftate, have been flightly noticed as criterions of intenfity. 
I fhall here add, that the efcape of negative electricity from a ball 
is attended with the appearance of ftrait (harp fparks with a 
7 hoarfe 
