THE PRESIDENTS ADDRESS. 101 
Mr. Russell, who recognized the precise agreement of the theory 
with experiment. It is important to add, that the lines of strain as 
pointed out by him were regarded as bearing some relation to the 
lines of polarization and depolarization produced by strained glass. 
As I have adverted to Mechanical Science, I cannot pass from the 
Subject without noticing an admirable application of siphons by Mr. 
Appold, which seems to surpass steam-pumping both in efficiency and 
in economy. ‘The air is exhausted from the siphons by a small en- 
gine, which works air pumps, and the quantity of water discharged 
by six siphons was no less than 50,000 gallons a minute, 
Nor should I omit noticing Mr. Peter’s most wonderful machine 
for microscopic writing, the working of which seems almost ineredi- 
ble. “ Within a circle of the three-hundredth of an inch, about the 
size of a transverse section of a human hair, the Lord’s Prayer can 
be written so as to be legible ; and a calculation has been made that 
with this machine the entire ae might be written twenty-two 
times in the space of a square ine 
“In an examination, which I ie saw somewhere, of the sums 
expended by the British Association for the advancement of Science, 
I observed a complaint that so small an amount, less than a tenth 
I believe, was spent for the encouragement and promotion. of the 
important department of Chemistry. The want of this pecuniary, aid, 
however, does not seem to have produced any injurious consequences, 
for there can hardly be a more satisfactory practical proof of the 
success with which this branch has been cultivated during the past 
year than the fact that three out of the four medals of the Royal 
Society were awarded for chemical researches. A notice of these 
investigations will, probably, be the most satisfactory review which. I 
can present of the progress of chemical science during the past year. 
The Copley Medal was awarded to Mr. Graham, Master of the Mint, 
for his discoveries in the employment of the diffusion of liquids in 
chemical analysis, or, as he terms the process of separation, dialysis. 
Compound substances are by him distinguished into colloids and 
erystalloids, and thees forms are regarded, the former as the dynamic, 
the latter as the statical form of matter. The importance of the 
results attainable by this new method justifies our ranking Graham 
with Dalton and Davy in the advancement of Chemical Science. __ 
_The Rumford Medal was awarded to Professor Kirchoff of Heidel- 
berg, as ajust recognition of his remarkable researches in Spectral 
