PROCEEDINGS. 
369 
that at all of them the regular morning change of declination 
was interrupted within a few minutes of the time of totality, and 
reversed in direction for half an hour to an hour, the average 
magnitude of the reversal being about 30", while the probable 
error of a reading is not over 3". At the single station where 
the intensity was observed a similar temporary reversal of the 
regular morning curve was noted, amounting to three times the 
probable error of the observation, the intensity being dimin¬ 
ished. ISTo satisfactory explanation of these reversals has yet 
been given. [Published in Journal of Terrestrial Magnetism, 
etc., voh v, p. 143 (1900).] 
530th Meeting. February 16, 1901. 
Vice-President Rathbun in the chair. 
Thirty persons present. 
Announcement was made of the death of Mr. S. C. Busey, 
for many years a member of the Society. 
Mr. Strother stated informally that there are now three 
processes for the manufacture of phonographic records which* 
promise absolute permanence, so the early idea of making records 
of speech for posterity now seems to be feasible. 
Mr. R. A. Harris read a Report from the Committee on 
Mathematical Physics, entitled A few questions in hydrody¬ 
namics. This reviewed briefly the kinds of problems in liquid 
wave-motion which have been considered in articles and treatises 
on hydrodynamics. But its chief object was to point out the 
lack of attention given to oscillations in bodies of water having 
incomplete boundaries, and in straits. These and other ques¬ 
tions must be investigated before satisfactory progress can be 
made in the theory of tides. [Published in this volume, p. 93.] 
This was discussed by Messrs. Hayford, Radelfinger, and 
Wead. 
Mr. J. F. Hayford reported on the Recent progress in geodesy, 
especially in the United States. The measurement of the 98th 
meridian has been continued; new and more rapid base-line work 
