Record. xlvii 



the points Pi 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 g, is such a function of the angu- 

 lar velocity &> which produces the deviation, that co <ioes not ap- 

 proach zero with g. 



Februaey 1, 1909. 



President Trelease in the chair; attendance 75. 



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- 

 mospheric 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 



