313 



Chicago^ Illinois, April 2d, 1858. 

 To Professor E. O. Kendall, 



Corresponding Secretary of the Am. Philos. Soc. Philada. 



Dear Sir, — I forward herewith to your care, for the library of the 

 American Philosophical Society, two volumes, as follows, viz. 



1. A bound copy of the American Almanac for the year 1848, 

 containing, at pages 366 to 369, a table of latitudes and longitudes of 

 a number of places in the United States, Canada, New Brunswick, 

 and Texas before it became a State of our Union, determined by my- 

 self and my assistants, to which I wish to invite the attention of the 

 Society. This table stands, in this volume, corrected of a kw typo- 

 graphical errors. 



2. A bound copy of my Annual Report on Lake Harbour Im- 

 provements, for the year 1857, 8vo. pp. 174, besides an "Addenda" 

 and an " Errata" at the end of the volume. I wish to invite the at- 

 tention of the Society, also, to a report at pp. 12 to 21, and 56 to 60, 

 of this volume, upon the determination of the longitude of the City 

 Hall or Court House of Chicago, west of Greenwich, giving it as 

 5A. 50m. 32S.08, or, in arc, 87° 38' 01 ".2. 



This result is based upon the longitude of the centre of the citadel 

 of Quebec, as determined by myself in the year 1842, while em- 

 ployed in ascertaining the north-eastern boundary of the United 

 States, under the treaty of that year with Great Britain. It will be 

 found announced in the American Almanac for the h, m. s. 

 year 1848, at pages 368, 369, as west of Greenwich, 4 44 49.65 



To this, assumed as a primary meridian, was add- 

 ed the difference of longitude obtained in May, 1857, 

 by Lieut. E. D. Ashe, of the British Navy, and my- 

 self, by means of electric signals transmitted along 

 the telegraphic wires, between the British Observa- 

 tory at Quebec, of which he is the Director, and my 

 observing station at Chicago, which h. m, s. 

 was thus found to be - - - 1 05 41.51 



Lieut. Ashe's observatory is east of 

 the meridian of the centre of the Que- 

 bec citadel, — 0.17 



And the dome of the City Hall or 

 Court House, of Chicago, is west of the 

 meridian of my observing station, - + 01.09 



VOL, VI. 



