B. TERRESTRIAL PHYSICS AND METEOROLOGY. 119 



EIVER CURRENTS AS AFFECTED BY THE EARTIl's ROTATION. 



In Dr. Giebel's Zeitschrift^ Dr. Dunker gives a somewhat 

 elaborate essay on the influence of the rotation of the earth 

 on the course of rivers, in which, after referring to his first 

 memoir published in 1860, he refers to that of Von Bayer on 

 the same subject, and states that his conclusion that rivers 

 flowinsf either northward or southward in the northern hem- 

 isphere should have their right-hand banks steeper, higher, 

 and more rapidly eaten away, applies also to the southern 

 hemisphere, with the exception that there the left-hand banks 

 are affected in that way. The further consideration of this 

 subject leads him to the consideration of the movement of 

 the winds on the earth's surface, and he gives a general 

 formula, published first by Hollbaur, as applicable to the 

 movement of any body on the surface of the earth, whether 

 solid, gaseous, or liquid. Dr. Dunker seems to consider only 

 bodies moving in tlie meridian either northward or south- 

 ward, and treats at some length of the influence of the river 

 in excavating and changing its channel. GiebeVs Zeits. ges. 

 JVaturw., 1875, 463. 



THE INTERNAL TEMPERATURE OF THE EARTH. 



The orio-in of the interior heat of the earth is treated of in 

 a few words by Professor Mohr, who states that if the in- 

 terior is still molten, it follows that the nearer we approach 

 this nucleus, not only must the temperature increase, but 

 must do so in an increasing ratio ; so that for a given in- 

 crease of temperature we require to penetrate into the inte- 

 rior of the earth through a decreasing number of feet. Now 

 the deepest artesian well as yet executed is at Sperenberg, 

 about twenty miles south of Berlin. This well was begun 

 in 1867, and has alreadj^ reached a depth of over 4000 feet, 

 at which depth Magnus measured the temperature (38.5 

 Reaumur) by means of his geothermometer. The observa- 

 tions of temperature that have been made in this well were 

 executed with the greatest care ; each position of the ther- 

 mometer being cut off" from connection with the upper or 

 lower portions of the well by plugging up the tube. The 

 most probable results of these measures are given in the fol- 

 io wins: table : 



