CAN 
end of 1749, he was engaged with his friend, 
the late ingenious Benjamin Robins, in 
making experiments to detei-mine the height 
to which rockets may be made to ascend, 
and at what distance their light may be 
seen. In 1750 was read at the Royal So- 
ciety, Mr. Canton’s “ Method of making 
Artificial Magnets, without the use of, and 
yet far superior to, any natural ones.” This 
paper procured him the honour of being 
elected a member of the Society, and the 
present of their gold medal. The same 
year he was complimented with the degi'ee 
of A. M. by the University of Aberdeen. 
And in 1751 he was chosen one of the coun- 
cil of the Royal Society ; an honour which 
was twice repeated afterwards. 
In 1752, Mr. Canton w^ so fortunate as 
to be the first person in England who, by 
attracting the electric fire from the clouds 
during a thunder-storm, verified Dr. Frank- 
lin’s hypothesis of the similarity of lightning 
and electricity. Next year his paper, entitled 
“ Electrical Experiments, with an Attempt 
to account for their several Phenomena,” was 
read at the Royal Society. In the same 
paper Mr. Canton mentioned his having 
discovered, by many experiments, that some 
clouds were in a positive, and some in a 
negative state of electricity: a discovery 
which was also made by Dr. Franklin in 
America much about the same time. This 
circumstance, together with our author’s 
constant defence of the doctor’s hypothesis. 
Induced that excellent philosopher, on his 
arrival in England, to pay Mr. Canton a 
visit, and gave rise to a friendship which 
ever after continued between them. Mr. 
Canton was a contributor to the Philoso- 
phical Transactions, and among many other 
papers, he sent, in 1765, an account of the 
transit of Venus of the 6th of June that 
year, observed in Spital Square. On the 
16th of December, the same year, another 
curious addition was made by him to philo- 
sophical knowledge, in a paper, entitled, 
“ Experiments to prove that Water is not 
incompressible.” And on Nov. 8, the year 
following, were read before the Society, his 
farther “ Experiments and Observations on 
theCompressibiUty of Water, and some other 
Fluids.” These experiments are a complete 
refutation of the famous Florentine experi- 
ment, which so many philosophers have, 
mentioned as a proof of the incompressibility 
of water. For this communication he had a 
second time the Society’s prize gold medal. 
Mr. Canton was a contributor to many 
other publications, particularly to the Gen- 
CAO 
tleman’s Magazine. In every period of his 
life he was an ardent promoter of useful 
science; and while philosophy lives fire 
name of Canton will not be forgotten. He 
died of the dropsy in his 54th year, on the 
22d of March, 1772. 
CANTONING, in the military art, is 
the allotting distinct and separate quarters 
to each regiment of an army; the town 
where they are quartered being divided in- 
to so many cantons, or divisions, as there 
are regiments. 
CANTUA, in botany, a genus of the 
Pentandria Monogynia class and order. 
Calyx three to five-cleft; corolla funnel- 
form; stigma three-cleft; capsule three- 
celled, three-valved, many-seeded; seeds 
winged. There are four species, natives of 
America. 
CANVASS, in commerce, a veiy clear 
unbleached cloth of hemp, or flax, wove very 
regularly in little squares. It is used for 
working tapestry with the needle, by pass- 
ing the threads of gold, silver, silk, or wool, 
through tire intervals or squares. This also 
is the name of a coarse cloth of hemp, un- 
bleached, somewhat clear, which serves to 
cover women’s stays, also to stiffen men’s 
clothes, and to make some other of their, 
wearing apparel, &c. It is likewise the 
name of a very coarse cloth made of hemp, 
unbleached, serving to make towels, and 
answering other domestic purposes. It is 
also used to make sails for shipping, &c. 
CAOUTCHOUC, or, as it is usually,- 
though improperly named, elastic gum, 
is a vegetable matter, which in several of its 
physical qualities, as well as in its chemical 
relations, has some similarity to vegetable 
gluten, and which so far agrees both with it 
and albumen, as to approach in the nature 
of its composition to animal matter. 
The substance to which the name of caout- 
chouc, or elastic gum, has been more parti- 
cularly given, was brought from Spanish 
America, in the form of hollow spheres or 
bottles, in which state it is still imported in- 
to Europe ; it was evident, therefore, tliat it 
had undergone some artificial preparation. 
Condamine gave the information, that it is 
the inspissated juice of a tree belonging to 
the family of the Euphorbia, which has since 
received the botanical name of Havea 
guianensis, or Havea caoutchouc. Incisions 
are made in the bark of this tree : a milky 
juice exudes, which is collected. It is ap- 
plied in successive coatings over a mould of 
clay ; is dried up by exposure to the sun, 
and afterwards by being placed in the smoke 
