373 



h. 771. S. 



Brought forward, -\- 01 06.82 



Reduction to the steeple of the Roman Catholic 



Church on Jackson street, Milwaukee, - — 0.5 



Steeple of this church is west of the meridian of Chi- 

 cago station No. 2, - - - - + 01 06.32 



Longitude of Chicago station No. 2, west of the me- 

 ridian of Greenwich, - - - - -}- 5 .50 31.15 



Determination 1st. 



Longitude of the steeple of the Roman Catholic 

 Church on Jackson street, Milwaukee, west of 

 the meridian of Greenwich, - - - -|- 5 51 37.47 



It will be seen that the coincidence in the results from the seven 

 electric signals sent from Chicago to Milwaukee, in the above series, 

 is not so close as those previously given in the cases of Waukegan 

 and Racine, or as those which follow, for subsequent dates, as given 

 from Chicago to Milwaukee. 



There is an extreme difference in the results derived from the 

 seven sent on the 23d of June from Chicago to Milwaukee, of seven 

 one-hundredths (jIq) of a second of time. This I attribute to the 

 little practice which the telegraph operator at Chicago had had, at 

 that date, in this species of experiments. 



On the afternoon of June 30th, I received information which made 

 it necessary that I should go again to Milwaukee on public business. 

 The journey afforded another opportunity to try the difference of longi- 

 tude between that place and Chicago, by two new sets of observations 

 entirely independent of those from which the above result is derived. 



On the night of June 30th (being the night before I started on my 

 second visit to Milwaukee), and on the night of my return to Chicago, 

 namely, July 3d, I made, at Chicago, the observations already given 

 under those two dates. They, combined with the following observa- 

 tions made at Milwaukee, and the telegraphic signals passed on the 

 the night of July 1st, and in the day of July 3d, give the two ad- 

 ditional determinations mentioned. 



