15 
its development, which, if adopted, will save thousands of 
dollars to our own and other municipalities in maintaining the 
purity of water supplied to the people. 
The recorded and published Proceedings of the Academy 
show that the Society has contributed in the past year to the 
advancement of science, and that its labors in this direction are 
worthy of commendation and encouragement. 
It will be always to the credit of Philadelphia that among 
its citizens are those who have given an aggregate of $120,250 
in the past seven years* towards the construction of a new 
building for the purposes of a society, formed for the cultiva¬ 
tion of the natural sciences, and during the same period even 
larger amounts have been given for the advancement of the 
fine arts, for educational institutions, for hospitals and other 
charitable establishments. A bountiful public spirit is spread¬ 
ing among us. The members of the Academy have reason to 
congratulate themselves that the career of the Society has won 
for it a high place in public estimation, made manifest in the 
favors it has received, and for which they are grateful. But 
numerous and liberal as contributions towards the accomplish¬ 
ment of this enterprise have been, its present condition compels 
us to seek earnestly a large accession to their number. There 
is no reason to doubt now that the new building will be finished 
sooner or later; but a certain patriotic pride urges that this 
work should be entirely completed by the spring of 1876, when 
the world has been invited to come and inspect the progress in 
civilization made by the nation during the first hundred years 
of its existence. 
Let us hope that those who truly estimate the importance 
and value of the diffusion of knowledge of the works of nature, 
and the promotion of original investigations in this great field, 
will at once give whatever aid they can. This work should 
not be left to be done by the opulent few. All may contribute 
something. The cost of knowledge is vast. But generally dif- 
* Taking the average population during seven years at 650,000, this con¬ 
tribution is equal to a yearly average of about 2 T 6 ^ cents a head. 
