B. TERRESTRIAL PHYSICS AND METEOROLOGY. 91 



works of Ferrel on this subject. Vienna Zeitschrifi far 3fe- 

 teorologie, 1S1 5, 290. 



THE EUROPEAN DROUGHT OF 1875. 



The period of great drought, which lasted from February 

 to April, 1875, in Europe, has been treated of by M. Lan- 

 caster, aid at the Royal Observatory of Brussels, who states 

 that this period merits our attention. The rainfall during 

 these three months has never, since 1833, been so small as 

 during this year. The mean of the forty-two years of obser- 

 vations at Brussels gives for the three months 144 millime- 

 ters, while the height for 1875 is only 46 millimeters, or less 

 than one third of the normal height. The pressure of the air 

 has generally been high. The temperature has been subject 

 to considerable variations, having been on the whole slightly 

 below the average. The wind has presented the most inter- 

 esting phenomena ; the predominance of northern currents 

 during March and April is especially remarkable. The 

 drought extended even to the middle of June, although by 

 that time a little water had fillen. Bullet. Acad. Roy. de 

 Belgique^ 1875. 



glaisher's observations of moisture in the atmosphere. 



In the annual memoir at the opening of the Gymnasium at 

 Sondershausen, the Director, Dr. Kieser, in an essay on the 

 moisture in the atmosphere, states that he has carefully com- 

 puted the extensive series of observations made by Glaisher 

 in reference to the absolute and relative humidity at differ- 

 ent altitudes. His results are presented in tables, showing 

 the state of the atmosphere at every one hundred meters 

 from the earth's surface up to a height of six thousand me- 

 ters. He concludes, first, that it is demonstrated that the 

 absolute humidity diminishes with the altitude, altliough ex- 

 ceptions are not uncommon ; second, that therefore the sur- 

 faces imagined to be drawn through the atmosphere defining 

 the regions of equal quantities of vapor have a wave shape, 

 depending upon purely local circumstances ; third, the quan- 

 tity of vapor is different at the same altitude in different 

 months; fourth, the density of the vapor diminishes much 

 more quickly than the density of the air as we ascend. Thus 

 the density at five thousand meters is about half of that at 



