ACADEMY OF SCIENCES. 161 



the horizontal thread at the instant the two stars are on the middle vertical 

 thread, and also at this moment noting the face time of the chronometer, that 

 we have the meridian altitude of a star whose declination is known, and 

 hence our latitude, and also the observed time of meridian transit of a star of 

 known right ascension, and hence a chronometer correction, simultaneously 

 with the observation that fixed our instrument in its meridian, the. error of 

 our chronometer, and our latitude, we can if desirable proceed at once to the 

 observation of additional stars for a closer time and to test our latitude and 

 azimuth. 



A reflecting circle or sextant mounted on an alt-azimuth stand is per se (i. e. 

 without an additional mirror) the instrument most convenient and ready for 

 finding by this method the meridian, latitude and time for the reconnoiterer, 

 explorer or land surveyor; and it may be found especially serviceable in hy- 

 drographic and geographical reconnaissances, whether in the course of an 

 exhaustive survey, or only a flying reconnaissance of a coast or continent. 



And from the readiness with which this method places "the transit" and 

 "zenith telescope" in the meridian it will be found useful and may prove ac- 

 ceptable to even the most conservative practical astronomer. 



Mr. Lowry finds that the B. A. catalogue offers an abundance of star pairs 

 of suitable magnitudes, declination-; and right ascensions. With the mean 

 places of stars brought up to Jan. 0. 1877, between the siderial times Oh. 07m. 

 and Oh. 57m. he finds 6 pair stars differing less than 3 seconds in right ascen- 

 sion, i pairs less than 7 seconds, 7 less than 16 seconds, and 5 less than 29 

 seconds. 



A yet neater method of getting a rnerid onal plane is to select three stars so that 

 stars A and B are of same declination and differ 10 or 15 minutes in right as- 

 cension, and star C differing several degrees from them in declination, but 

 with a right ascension equal to one-half of the sum of those of stars A and 

 B. Now observe the coincidence of stars A and C in telescope field and read 

 horizontal circle, and then the coincidence of stars B and Cin the field of view 

 and read the horizontal circle, then set the vernier at the point midway be- 

 tween these horizontal circle readings and our telescope is in its meridian. 



The President announced that the Council and Trustees had 

 appointed the following Nominating Committee : Horace Davis, 

 J. H. Smythe, S. B. Christy, Wm. Norris and P. B. Cornwall. 



Dr. Wozencraft was introduced by Dr. A. B. Stout, and made 

 some remarks on the feasibility of reclaiming the Colorado Des- 

 ert of California. 



