4 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES 
The Astronomical Section has an equatorial telescope with 
a four and one-half-inch objective, capable of showing the 
dises of the planets, separating many beautiful double stars, 
and resolving numerous star-clusters. Current astronomical 
events are reported and elucidated at these meetings. 
Geologists and mining engineers familiar with the geo- 
logical formations of the great Southwest and its rich and 
varied mineral products, have made the evenings devoted to 
the Geological Section particularly attractive. Charts of the 
structure and workings of famous mines, theories of vein 
formations, the part that chemical action is playing in aggre- 
gating and disseminating the precious metals, and theories of 
the origin and occurrence of our immense fields of crude oil 
in Southern California, have proved profitable subjects for 
discussion at these meetings. 
The Biological Section has done some of the most useful 
work of the Academy. Its wide range of subjects, the ability 
with which they have been discussed, the excellence of the 
illustrations used, the beautiful slides which have been pre- 
pared, and the free use of microscopes of great magnifying 
power, have added greatly to the charm of these meetings. 
Astronomer in an Iron Tank. 
While Prof. David Todd, the astronomer, was on the top of 
the Andes last summer, nearly three miles above sea level, ob- 
serving Mars and taking his marvellous photographs of its 
canals, he worked for a time in an iron tank about six feet 
square, into which the air was pumped until the pressure 
within was the same as that at the level at th esea. The com- 
partment was lighted by electricity and was connected with 
the outer world by telephone. This device enabled the profes- 
sor to do work which would otherwise have been impossible 
at that great elevation. 
