1901.] NATURAL SCIENCES OF PHILADELPHIA. 745 
provided. The work of expansion is still in progress, and to 
understand properly the advance that has been made it is necessary 
to revert again to the removal of the Academy to its present quar¬ 
ters in 1876. 
At lhat time only a part of the building as originally planned 
had been completed, and the collections and library of the Academy 
even then practically filled all the available space. The constant 
increase during the subsequent ten years caused such overcrowding 
that the systematic arrangement of the museum became an impos¬ 
sibility, and much valuable material was practically inaccessible. 
In 1889 and 1891 two appropriations of 850,000 each were 
secured from the State Legislature. These sums, together with 
private subscriptions, made possible the much-needed additions to 
the premises. The Lecture Hall was completed the following year, 
and formally opened on February 22, 1892. Lectures previously 
given in the Library have since then been delivered in the new 
Hall, which has been furnished with a lantern and screen and 
seating accommodations for 350 persons. 
The new wing of the museum was not completed until some 
years later and was finally opened on October 20, 1896. 
Owing to the lack of funds only two floors could then be 
opened, and only a part of one of them was furnished with new 
cases. Since then, however, new cases of plate glass with oak or 
mahogany woodwork have almost entirely replaced the old ones on 
these floors, as well as in portions of the old building, and the 
furnishing of the third floor of the new Museum is so far advanced 
that it will be opened during the coming year. 
In the character and care of the various collections the greatest 
changes have takeD place, mainly since the recent increase in our 
endowment, though in several departments the plans were laid 
and work begun several years ago. The old idea of exhibiting 
every specimen has been dispensed with, and the need of study 
collections of large series of specimens has been recognized. 
Large numbers of birds and mammals, especially types and 
unique specimens, have been unmounted and stored in moth-proof 
cabinets, free from light and dust, and their preservation insured. 
These have been arranged in the study rooms, where they can be 
easily examined, while still larger numbers of similar study speci¬ 
mens have been added by purchase and gift. A corresponding 
