1893. ] NEW YORK ACADEMY OF SCIENCES. 75 
single day—might,in his long experience, with every possibility 
be depended on. 
SECTION OF ASTRONOMY AND PHyslics. 
Professor Rees in the chair. The secretary read a paper by 
Mr. Herman 8S. Davis, Fellow in Astronomy at Columbia Col- 
lege, entitled ‘‘ Note on Bessel’s determination of the relative 
parallaxes of 1 and 4 Cassiopeiz.” Mr. Davis had re-reduced 
the observations of right ascension difference of the two stars 
made by Bessel in the years 1814 to 1816, and printed in Engel- 
mann’s ‘“‘Abhandlungen von F. W. Bessel,” vol. 2, p. 215. Em- 
ploying the Auwers, proper motions of the two stars and 
introducing into the Besselian equations a term to allow for dif- 
ferential proper motion, Mr. Davis arrives at the value : 
Parallax of / relative to 4 Cassiopeie —-+- 0. //02 + 0’ .24. 
Where Bessel had obtained SERN eT ORS OL) 
It will be seen that the new reduction diminishes materially 
the probable error of the result, in spite of the fact that the in- 
troduction of the proper motion term into the parallax equa- 
tions has lessened the weight of the determination of the parallax 
itself. Mr. Davis’ result is in very close though perhaps acci- 
dental accord with that derived from Mr. Rutherfurd’s photo- 
graphic measures, which was + 0’’ .04 (Annals N. Y. Academy, 
Volivintips, Il!) 
Professor William Hallock read a paper on “ The Theory of 
Geysers,” in which he described his researches upon the geysers 
of the Yellowstone Park, and explained their action. A glass 
model geyser was exhibited, in which the internal arrangement 
and action was plainly shown. Steam was supplied to the 
model from a small copper boiler, and it reproduced very suc- 
cessfully the remarkably regular periodical eruptions which in 
nature are caused by the supply of steam from the interior 
heated strata of the earth. 
STATED MEETING. 
November 20th, 1893. 
Vice-President Osporn in the chair, and twenty persons 
present. 
The following paper was read by title: 
