382 



h. m. s. 



Brought forward, + 01 06.20 



Reduction to the church steeple as before (see Deter- 

 mination 3d) - - - - - + 0.03 



Steeple, west of the meridian of Chicago observing 



station No. 3, - - - - + 01 06.23 



Longitude of Chicago observing station No. 3, - 5 50 31.20 



Determination Atli. 



Longitude of the said steeple, west of the meridian of 



Greenwich, - - - - - 5 51 37.43 



Summary. Longitude of this steeple: 



By Determination 1st, of June 23d, 1858, - 5 5137.47 



By Determination 2d, of July 1st, „ - 5 51 37.53 



By Determination 3d, of July 3d, „ - 5 5137.53 



By Determination 4th, of July 6th, „ - 5 51 37.43 



Mean^ giving each determination an equal weight. 



Longitude of the steeple of the Roman Catholic 

 Church on Jackson street, Milwaukee, west of 

 the meridian of Greenwich, - - 5/i. 51 7/i. 375.5 



Equal, in arc, to ... 87° 54' 22".5 



I confess I was surprised, when the several computations were 

 completed, at the very close coincidence of these four determinations. 

 They may be due, in some measure, to a fortunate concurrence of 

 circumstances of which I am altogether unconscious. No one can 

 expect such results, always, from observations with a sextant of the 

 ordinary size, depending on the steadiness of the hand for its support; 

 yet I do not hesitate to say, from long experience in observing with 

 astronomical instruments — both portable and those permanently 

 mounted on stone pillars — that the correct time may be obtained by 

 a practised observer, with a good sextant and artificial horizon, with- 

 in a small fraction of a second, by twenty or thirty minutes time spent 

 in observing on two stars of nearly the same declination, whose pla- 

 ces, as cjiven in the catalogues, are well determined — the one to be 



