Astronomy. 357 



very favorable to the blooming of plants, while a moist atmos- 

 phere is extremely unfavorable. This favorable effect was indi- 

 cated in the former case especially by the precocity of the vege- 

 tation, which was so great as to allow of having three crops 

 produced in a single season. From the researches of Gain, it 

 would appear as if irrigation had advantages which have not 

 hitherto been fully appreciated. g. l. g. 



IV. Astronomy. 



1. Transactions of the Astr. Observatory of Yale University, 

 vol. i, Parts III and IV. 



, Part III. Triangidation of Stars in the Vicinity of the North 

 Pole ; by William L. Elkin. 



This investigation was undertaken in consequence of a request 

 from Prof. Pickering, of Harvard, to determine with the heli- 

 ometer the relative positions of a few stars near the North Pole to 

 serve as fundamental points for a photographic survey of that 

 region. The author enlarged the plan to include 24 stars, nearly 

 all of those bright enough to be well measured with the instru- 

 ment within If degrees of the Pole in 1888. The plan of meas- 

 urement adopted consisted in measuring all the intermutual dis- 

 tances between the 24 stai'S within the range of the heliometer, 

 145 of all the 2^6 possible combinations. These were observed 

 each three times and a zone of stars ending with 51 Hev. Cophei 

 and S TIrsae minoris was taken for an independent and simulta- 

 neous determination of the scale value. The adjustment of the 

 measurement was carried out by a series of successive approxima- 

 tions, the system or coordiuates used being that proposed by 

 Fabritius, which offers great advantages for stars near the Pole. 

 A first set of approximations revealed the existence of a syste- 

 matic error in the measures, which being duly allowed for, a final 

 system was derived, which was referred to the Pole by means of 

 the Berlin Jahrbuch places of a and A TIrsae minoris. These 

 final places are also given in the usual system of right ascension 

 and declination together with tables for precessional changes. 

 The probable errors were derived by a process suggested by Dv. 

 Gill. The proper motions of the stars are small ; approximate 

 values can be inferred from the comparison given with Carring- 

 ton's places for 1855. 



Part IV. Determination of the Orbit of the Comet 1847, VI, 

 by Maegaeetta Palmer. 



This comet was discovered on Oct. 1, 1847, by Miss Maria 

 Mitchell at Nantucket, Mass., and subsequently independently by 

 de Vico at Rome, by Dawes in England, and by Madame Riimker 

 at Hamburg. Its orbit had been investigated by Dr. George 

 Riimker in a nearly exhaustive manner, but a slight improvement 

 seemed possible by a new discussion of the places of the compari- 

 son stars, by introducing modern places of the sun and by taking 

 the planetary perturbations into consideration. This, together 



