TRANS. ST. LOUIS ACAD. SCIENCE. 



Remarks on the Results. 



The chart which accompanies this report represents the decli- 

 nation determinations thus far made in Missouri, and we have 

 added a map of the adjoining State of Iowa in order to represent 

 the results of a preliminary survey of Iowa by Dr. G. Hinrichs. 

 The isogonic lines here shown in Iowa are given as published 

 by him,* except that the 9° and 8° lines in central Iowa are 

 thrown half a degree to the east, my results four miles west of 

 Iowa City differing from Hinrich's determinations in the Uni- 

 versity campus by this amount. The determinations made in 

 the city have been very discordant, and not much reliance is to 

 be placed upon them.j 



On inspection of the chart of isogonic lines it will be ob- 

 served that these lines exhibit remarkable flexures, which evi- 

 dently bear a very intimate relation to the drainage systems of 

 the regions. 



Prof. Hinrichs had detected these flexures in 1878, but his sta- 

 tions were so few in number and so widely separated that he did 

 not feel perfectly certain of the facts. My own work, begim a 

 little earlier during the same year, did not cover enough ground 

 to bring out these features during 1878. During the summer of 

 1879, however, we pushed the work south of the Missouri river 

 and west of Lon. 92° 30' , and the evidence on this point was 

 placed beyond all question. It is perhaps worthy of remark, that 

 each had made arrangements for the survey of his own State 

 without the knowledge of the other. 



The explanation which Prof. Hinrichs gives of these irregu- 

 larities is contained in his "Theory of the Magnetism of the 

 Earth," published in Copenhagen in i860. 



His hypothesis is that the earth's magnetism is due to the mo- 

 tion (rotation and translation) of the earth in ether, thus giving 

 rise to ether streams in the earth ; and he then predicted that 

 ocean currents, by virtue of the motion of the water, would, when 

 properly dii-ected, accelerate or retard the ether stream, thus in- 



* See Weather Report for April, 1878. 



The Iowa stations are indicated on the map thus "o." 

 t Compare my own determination at station a in the present report. 



