B. TERRESTRIAL PHYSICS AND METEOROLOGY. 107 



so much greater in the antarctic than in the arctic regions. 

 One of the most important practical results attending the 

 publication of'Rikatcheff's memoir is the stimulus that it has 

 given, and probably will give, to the application of Riihl- 

 mann's methods for the determination of altitudes by means 

 of the barometer. According to this author, we should, if 

 possible, employ only monthly or annual means for deter- 

 mining altitudes barometrically, and should (especially when 

 only a few observations are available) employ the readings 

 of the barometers at two or more known stations in order to 

 deduce therefrom the temperature of the air without relying 

 on thermometric observations. From the isobaric charts 

 given by Rikatcheff we can find the average normal height 

 of the barometer for any month whatever in Eastern Russia 

 within less than one twenty-fifth of an inch, and in Western 

 Russia within one fiftieth of an inch, and the average annual 

 mean pressure of any point in Western Russia within one one- 

 hundredth of an inch. Wild's "Repertorium" IV., art. 6. 



OX THE TIDES IN THE ROADSTEAD OF FIUME. 



In a recent prize essay by Professor Stahlberger on the 

 tides in the roadstead of Fiume, the author, from a study of 

 observations extending over thirty-seven lunations made by 

 means of a self-recording tide-gauge, shows that with a ris- 

 ing barometer there occurs a diminished height of water, 

 and, conversely, with a diminished pressure an increased 

 height of water. In connection with the barometric press- 

 ure, the northerly and southerly winds exert their influence 

 to respectively increase and diminish the water level. With 

 the southern winds, the curves showing the height of the 

 water are comparatively smooth and regular. With the 

 northerly winds, however, they vary according to the strength 

 of the wind, showing greater or less irregularities. The pe- 

 riodic movements of the ocean level are subject to two prin- 

 cipal oscillations, depending on the moon, and two other 

 principal ones depending on the sun. The regularity of this 

 phenomenon is complicated very much by the fact that the 

 tidal waves that reach Fiume come from the Mediterranean. 

 The reason why the twenty-four-hour oscillation is compara- 

 tively large, while the twelve-hour is Aveak, depends, according 

 to Stahlberger, upon the configuration of the Adriatic Gulf. 



