Record. xlvii 
the points P, and P, coincide, the apparatus becomes a plumb line. 
Then the point P is the image which the observer sees of his eye in 
the quipotential surface which pass through P. 
An apparatus was shown which illustrates the first theorem, and 
an apparatus was described which illustrates the second theorem. 
In the second apparatus the equipotential surface is actually assumed 
by the surface of water which reflects light. 
Incidentally, it was shown that in the conical pendulum the 
angle of deviation from the vertical §, is such a function of the angu- 
lar velocity @ which produces the deviation, that g does not ap- 
proach zero with - §. 
Fresruary 1, 1909. 
President Trelease in the chair; attendance 7). 
The program of the evening had been especially ar- 
ranged in celebration of the centenary of the birth (Feb- 
ruary 2, 1809) of Dr. George Engelmann, one of the 
founders of the Academy, and its first president. Stand- 
ing not only among the leading medical practitioners of 
the last generation, Dr. Engelmann was also one of the 
foremost botanists of his day; for, during the many years 
of an active, useful life, most of which was spent in Saint 
Louis, he found sufficient time, in the leisure hours of his 
practice, to devote to a series of most valuable scientific 
investigations. And, moreover, in addition to his profes- 
sional and botanical labors, he was a zealous meteoro- 
logical observer, keeping observations pertaining to at- 
mospherie phenomena for over forty years. 
Dr. Baumgarten opened the program with a very inter- 
esting paper entitled ‘‘The Personality of Engelmann.’’ 
Dr. Baumgarten, having been a personal friend of the 
physician and botanist, was peculiarly well fitted to han- 
dle this subject, which he treated in a reminiscent way, 
making characterizations of a personal rather than more 
biographical nature. This tribute of Dr. Baumgarten to 
the memory of his friend was one that bespoke only the 
most sincere friendship for Dr. Engelmann, and the 
highest appreciation of his character and achievements. 
Professor H. A. Wheeler presented a paper on ‘‘En- 
gelmann’s Contributions to Geognosy.’’ For Engel- 
mann’s reputation extended beyond the borders of his 
master work in botany and his devotion to local meter- 
ology; although his influence in geognosy is perhaps due 
