ARTICLE XVII. 



Astronomical Observations, made at several Places in the United States. By 



J. N. Nicollet. Read May 6, 1842. 



Baltimore, (Md.,) at the Botanical Garden of St. Mary's College. 



Latitude 39° 17' 55". Longitude 5^ Q'^ 30'. (?) 



I. A transit of Mercury, observed May 4, 1832, by J. N. Nicollet. 

 Beginning of the transit; invisible in the United States. 



{Interior contact of limbs, 22^ 28'" 37^2 "j 

 Centre of Mercury, 29 33 .9 i. Mean time of the place. 



Exterior contact of limbs, 30 46 .6 J 



Remark. — The morning w^as generally cloudy, but, still, successive openings 

 of several minutes' duration afforded ample opportunities of following up the 

 progress of the transit, during vs^hich the planet was very distinct, and its out- 

 line well defined. The disc of the sun, during the second and third observa- 

 tions, was very clear, which circumstance leads me to believe that the times of 

 these last are very correct. The observations were made with a DoUond tele- 

 scope, having a magnifying power of about 100. 



The Rev. Mr. A. Verot, Professor of Mathematics and Natural Philosophy 

 in St. Mary's College, recorded the time and other circumstances of the obser- 

 vations. 



II. Immersion by Moon's dark limb of y. Librae, observed July 7, 1832, at 

 10'' 00"" 04' .63, mean time, by J. N. Nicollet. Sky cloudy at intervals, but 

 clear at the moment of the observation. A Dollond telescope, having a mag- 

 nifying power of about 100. 



VIII. — 4 c 



