A. D. Bache on Declinometer Observations. 37 
relation of the law at these stations resulted from such a com- 
ison, and farther examination may bring to light other de- 
pendencies of a mutual character. 
According to the latest determination the position of the Gi- 
rard College observatory is in latitude 39° 58’ 23” (north), and 
in longitude 75° 10’ 05’ =54 00™ 40s°3 west of Greenwich. From 
it Toronto bears 38° 45’ west of north (true) and is distant about 
334 statute miles. 
gous disturbances. The following discussion will afford a con- 
tribution towards the determination of the epoch of the occur- 
rence of a minimum in certain phases of the magnetic variation - 
and disturbances, corresponding to a minimum of the solar spots. 
The method of reduction is substantially the same as that adopted 
by General Sabine. Earlier investigations of Dr. Lamont and 
those by Mr. Kreil differ from his in not including the discussion 
of the disturbances in connection with the period in question. 
Zi 
cess was repeated when necessary, so that in all cases, hE 
differing eight scale divisions or more from the mean were ex- 
cluded. The last mean thus obtained for each observing hour 
and each month has been called “the normal.” These values 
have been tabulated and are given for each month and year 
Separately, together with such corrections as the omissions or in- 
terruptions demanded. The bi-hourly, and afterwards the hourly 
readings (and their means) were made 194™ after the hour so as 
to correspond to an even Guttingen hour (diagram A). 
* 
] 
