34 
ABBE. 
The chemical composition of the atmosphere was scarcely 
suspected or suggested by any of the ancient writers, and we 
must come down to the days of Priestley, Scheele, and La- 
voisier to find anything known on the subject. 
The idea that air has physical properties, such as mass or 
weight, and that it could offer material resistance to bodies 
passing through it, was often expressed, but the properties 
were not satisfactorily observed and measured until the days 
of Galileo in Italy and Stevin in Holland. Galileo, having 
a pump for compression, was able to show that air is a com- 
pressible gas ; but having no means of pumping the air out 
of a receiver, he was unable to entertain the idea of a vacuum, 
and in fact explained the rise of water in a pump as due to 
the horror of a vacuum, until his pupil, Torricelli, presented 
the idea of the elastic pressure of the atmosphere. 
Other mechanical properties of the gases of the atmos- 
phere, such as inertia, centrifugal force, expansion with heat, 
densitv, elastic resistance, and viscositv, were entirely un- 
c/ j ' « j 
known to the ancients, and were first clearly set forth by 
Galileo, Torricelli, Stevin, Descartes, Huyghens, Hook, 
Boyle, and Sir Isaac Newton. 
SOCIETIES FOR RESEARCH IN METEOROLOGY. 
The association of men into academies or some equivalent 
organizations dates back to the remotest history. The wise 
men or learned priests and philosophers of Persia, Assyria, 
and Egypt were organized in companies connected with tem- 
ples of worship and as official astrologers in connection with 
the astronomical observatories. The so-called library or mu- 
seum at Alexandria, Egypt, founded by Ptolemy Philadel- 
phus 250 B. C., became the center of the most famous school 
of science of all antiquity, and developed into a true univer- 
sity, which lasted until overthrown by the Arab Mohamme- 
dans. To it we owe Eratosthenes, Euclid, Diophantus, 
Ptolemy, Synesius, and many other mathematicians and as- 
tronomers. The observatory of Ulugh Bey and Tamerlane 
at Samarkand was for twenty years, 1430 to 1449, a center 
for the revival of Arabic science, while at the same time in 
