116 On Addition and Subtraction of Algebra. 
connexion with the common galvanic battery, depends upon the 
relation of the fluid and metal, and not upon that of the metals 
merely.. ‘These experiments should be repeated, with the aid of 
the insulating glasses, placed so as to receive the coils of your 
machine. 1 should be very curious to know whether the effects 
would be the same; and as I now have the glasses, I shall, as 
soon as possible, try this experiment. We must look to you, sir, 
for the explanation of this singular incompatibility between the 
two instruments. At present, I confess myself unable to explain 
it. It may, very possibly, lead to important results, and may 
have a bearing, such as I have not now time to discuss, on your 
own peculiar theory. 
I would state that the mode of connecting the two batteries 
was varied in every form which occurred, not only to myself, but 
to several able scientific gentlemey, who were present at these 
experiments, and who were equally with myself surprised and 
confounded by their results. 
I congratulate you upon the brilliant additions which you have 
made to our experimental means, in this department of know- 
ledge. Along with your invention of the compound Blowpipe, 
they fairly entitle you to the gratitude of the scientific world, not- 
withstanding the uncandid attempts which, in relation to the 
Blowpipe, I am sorry to see, are still persevered in, to deprive 
you of the credit which you so richly deserve. 
I remain, as ever, your friend and servant, 
Prof. Robert Hare, M.D. B. SILtiman. 
XXVIII. On Addition and Subiraction of Algebra. By Mr. 
PauL Newron. 
To Dr. Tilloch. 
Old Assembly House, Newark, Feb. 1], 1822. 
Sir, — Tue confused notions which have hitherto prevailed 
concerning Addition and Subtraction of Algebra, and the conse- 
quent inconsistency with which our best authors have treated 
these rules, incline me to. indulge the hope that you will adinit, 
on this subject, a few observations as a supplement to what you 
kindly inserted in No, 285 of your distinguished and invaluable 
Magazine. 
** Time, which overthrows the illusions of opinion,’ must esta- 
blish, in its progress, just regulations of quantity. I shall again 
refer to Mr. Bonnycastle’s treatise, for instances of injudicious 
arrangement, not from any invidious motive of detracting from 
his merit, but because his treatise is, I believe, the last great 
work on the subject, anc because his errors are calculated to ee 
ead, 
