3. A. Brun. Recherches sur rexhalatiou volcanique. Geneve 1911. 



4. L. Day and E. S. Shepherd. Water and volcanic: activity. Bull. Geol. Soc. 

 Am. Vol. 24 1913 p. 573-606. 



5. T. H. King. Principles and conditions of the movements of groundwater 

 19th. An. rep. U. S. Geol. Surv. 1897—98 Pt. II. 



6. G. R. VAN Hi.SE. A treatise on Metamorphi.'^m U. S. Geol. Surv. Washington 

 1904 p. 132 and 133. 



7. J. Versluys. Het beginsel dor beweging van het grondwater. Amsterdam 

 1912 p. 126 et seq. See also: E. Ramank. Bodenkunde. Berlin 1911 ; Verslag 

 van eene Commissie van de Kon. Ak v. W. te Amsterdam. 1887, and others. 



8. F. D. Adams and L. V. King. Journal of geology Vol. XX No. 2 p. 97 — 

 138. 1912. 



Astronomy. — "Ohxerratlon of the moon during the EcHpni' of the 

 sun on Aug. 21 1914 and of the Transit of Mercury on 

 Nov. 7 1914, made in the Leiden Observatory. By J. Woi.tjkr 

 Jr. (Cominiinioated by Prol'. E. F. van de Sandk Bakhi yzen). 



(Communicated in the meeting of April 23, 1915). 

 I. .Solar-eclipse of August 21, 1914. 



Daring the eclipse of Aug. 21 1914, sun and moon passed over 

 the meridian. At the suggestion of Professor E. F. van de Sande 

 Bakhuyzen I have observed the declination of the south-limb of tlie 

 moon with the transit-circle. The results of this observation including 

 details concerning the method of reduction will be given here. 



In order to obtain as large a number of pointings as possible 

 Professor Bakhuyzen kindly undertook the reading of the microscopes 

 (including those for the observation of the nadir). 



The observed declination depends on the observation of the nadir. 

 As two of the pointings had naturally to be made far outside the 

 meridian, it was necessary to give special attention to the inclination 

 and curvature of the horizontal wires. In 1911 an investigation on 

 these points had been made; for this purpose a collimator provided 

 with a level had been mounted on the soutii-pier; by means of 

 one of the foot-screws the middle of the two horizontal wires of 

 the collimator was pointed on various points of the horizontal wires 

 of the meridian-telescope; by reading the level each time the incli- 

 nation of the oi)tical axis of the collimator liecomes known and 

 thus that of the line from the middle of the objective to the special 

 point of the horizontal wire on which has been pointed. 



The pointings were made on five difterent points of each wire, 



