2 CHARLES CARPMAEL: 
might otherwise have occurred in it, and if the paper has been already written, it will 
give the author an opportunity of removing the blemishes before publication; or if the 
error which is detected should seem to require it, he may withdraw the paper altogether. 
Dr. Wilson, the President of this Society for the present year, recently said to me that, 
when he first came to Canada many years ago from Edinburgh, there were two things that 
he missed above all others; the first was the want of a good library to which he could 
refer (for there was then no library worthy of the name in Toronto), and the second was 
the absence of all opportunity of discussing with others, interested in such work as he 
might be engaged in, the various points to which his attention might be turned during 
the progress of his investigations. So many points would be discussed, he added, at 
meetings of the Royal Society of Edinburgh and in other learned societies, that the 
author of any literary or scientific work would generally have his views so modified 
and enlarged before its completion, that he would find it impossible to say, how much was 
really due to his own researches, and how much had been suggested in these discussions. 
It must not be forgotten that what we, as scientific workers, should aim at, is not so 
much the production of a large number of papers, as that such as we may produce shall 
contain new scientific truths, new scientific deductions from old principles, or new and 
improved methods of deducing facts already known, and that they may be as far as pos- 
sible free from error. When once a paper is printed, in which deductions are drawn from 
erroneous premises, or erroneous deductions from true premises, this paper may be read 
by many who will be unable to detect the errors and who may copy them and so spread 
not truth but error. When once widely spread, it is often the work of a very long time 
before the erroneous ideas thus promulgated become eradicated. 
A good instance of this difficulty is the erroneous impression very generally held by 
mathematicians as to specific gravity and density. The specific gravity of a substance is 
commonly taken by them as the weight of a unit of volume of that substance, thus making 
the specific gravity vary from place to place, and introducing unneccessary complication 
into all calculations involving this quantity. The density of the substance is on the 
other hand taken as the mass of a unit of volume of the substance. Eyery practical physic- 
ist must know that specific gravity, like density, is determined by a comparison of the 
masses of equal volumes of the given and a standard substance ; yet in all our elementary 
text books on hydrostatics, at least in the English language, the above way of defining 
specific gravity is still retained, although in the elementary text books on mechanics it is 
clearly pointed out that what are ordinarily called standards of weight are, in the mathe- 
matician’s way of defining weight and mass, in reality standards of mass. 
In France also, at least a few years ago, both terms were used ; and there, according to 
Millar, in tables of specific gravity the unit was usually water at zero cent., while in tables 
of density the unit was water at 4°c. 
If in these countries errors or unnecessary complications, once introduced, are so per- 
sistent, in Canada, or at any rate in Ontario, they are likely to be still more so. We are 
here having introduced into our schools a uniform series of text books, so that if any errors 
creep into them, not the pupils in one school only, but in a whole generation, will be 
brought up in the same errors, which will not therefore stand so good a chance of being 
corrected by the after mixing together of pupils from different schools. 
Although then, whatever precautions we may take, as Science advances, we shall 
