On the Constant Currents in the Air and in the Sea. 21 



greatly different, on an average, from that found in the zodiacal 

 light. Although no certain conclusions can be drawn from ex- 

 periments like these, their results are not inconsistent with the 

 supposition in reference to which they were made, but, so far as 

 they go, tend to confirm it. The results of the investigation 

 may be summarized as follows : — 



1. The zodiacal light is polarized in a plane passing through 

 the sun. 



2. The amount of polarization is, with a high degree of pro- 

 bability, as much as 15 per cent, but can hardly be as much as 

 20 per cent. 



3. The spectrum of the light is not perceptibly different from 

 that of sunlight, except in intensity. 



4. The light is derived from the sun, and is reflected from 

 solid matter. 



5. This solid matter consists of small bodies (meteoroids) 

 revolving about the sun in orbits crowded together toward the 

 ecliptic. 



Yale College, April 6, 1874. 



IV. The Constant Currents in the Air and in the Sea : an At- 

 tempt to refer them to a common Cause. ByBavon N. Schil- 

 ling, Captain in the Imperial Russian Navy*. 



Introduction. 



THE currents of the sea and of the atmosphere have been 

 observed from times immemorial ; much has been written 

 on both ; but, unfortunately, science has hitherto made but very 

 unsatisfactory progress in this department. The laws which 

 govern them are still very little understood ; and their origina- 

 ting causes, in particular those of the great ocean- currents and, 

 indeed, of the trade-winds, are as good as totally unexplored, 

 since, on closer examination, every explanation yet given must 

 be regarded as not at all sufficient. A complete knowledge and 

 a comprehensive theory of all currents will long remain impos- 

 sible, because the currents are subject to the action of very 

 various influences, and these, accompanied by very manifold cir- 

 cumstances, exhibit themselves in such different fashions and 

 are so complicated that it has not hitherto been possible to sub- 

 mit them to exact mathematical analysis. Apart from the theo- 

 retical difficulties, practice often opposes insuperable obstacles 

 when we wish to trace a current through the whole extent of its 



* Translated from a separate publication communicated by the author, 

 entitled Die bestandigen Strdraunyen^ &c, Berlin, 1 874. 



