358 SCHLESINGER— VARIATIONS OF LATITUDE. [April 24. 



held up very well. It is not too much to say that at the present 

 time all but one of the numerous explanations of this class have 

 been disposed of ; this exception deserves a brief mention, particu- 

 larly as it calls loudly for the attention of the meteorologist. Let us 

 suppose that the layers of equal density in the atmosphere above a 

 station are not horizontal, but that they are sensibly inclined. If 

 this occurs without our knowledge, as it would under ordinary cir- 

 cumstances, then we should apply refraction to our observations in 

 a slightly erroneous way and we should derive a value for the lati- 

 tude that is not quite correct. Let us suppose further that this 

 effect were a world-wide one and that in any given month there 

 would be a pronounced tendency for the inclination to be in the 

 same sense in all latitudes, north and south, as well as in all longi- 

 tudes. Then we should have a set of circumstances that would ac- 

 count for the Kimura term as an atmospheric effect, and therefore 

 it would be excluded as a real variation of latitude. So far as the 

 astronomer is able to testify, the evidence is against the occurrence 

 of such tilts in the atmosphere. The inclination required to account 

 quantitatively for the amplitude of the Kimura term is over two 

 minutes of arc, or a slope of about one part in fifteen hundred. 

 Presumably in a few years we shall be able to say something more 

 definite as to the possibility of the existence of such conditions. 

 My own opinion is that this explanation, like so many others of 

 similar character that have been suggested for the Kimura term, 

 will be found untenable. Further I venture to think that latitude 

 variations as a whole will find their explanations less on the surface 

 of the earth and more in its interior than seems now to be the 

 generally accepted opinion. 



Allegheny Observatory, 



University of Pittsburgh. 



