On the Sixth Section of Bessel's Astronomical Observations. 1 7 



( = 32), and it will give 3 J atmospheres, or 56^ lbs. per square 

 inch for the average force on the plunger during the whole 

 stroke, when compressing gas equal to 32 atmospheres. 



Therefore as the pump acts but singly, if a fly-wheel of 

 sufficient weight be employed, a power equal to about 30 lbs. 

 on every square inch of the area of the plunger will be nearly 

 adequate to the working of the pump. 



It' gas of the pressure of only 20 or any other number of 

 atmospheres less than 32, be required, the necessary average 

 power for producing it can readily be ascertained from the 

 same diagram; for let the line Km represent the proposed 

 pressure, then cutting off the upper part of the figure by the 

 line m?i, parallel to the base AB; and calculating the remain- 

 ing area, in the manner already described, it will give the re- 

 quired power. And if the pressure should be required to be 

 more than 32 atmospheres, then by increasing the height of 

 the diagram towards a c in the manner already shown, we 

 can also in that case estimate nearly the necessary required 

 power. 



III. Introduction to the Sixth Section of 'Bessel's Astronomical 

 Observations. 



[Continued from vol. lxiii. p. 443.] 



6. Observations of circumsolar Stars. 



THE reduction of the observations of these stars to the 

 beginning of the year 1820, was undertaken by Mr. Arge- 

 lander, who has been employed since the autumn of 1820 as 

 assistant in the Observatory, and has already obtained by ob- 

 servation and calculation many results useful to science, of 

 which I expect to publish in the next section of my Observa- 

 tions such parts as belong to the subject of this work. The 

 fundamental catalogue of Konigsberg is the foundation of the 

 present computation ; the reductions have been made by the 

 small tables, the publication of which Professor Schumacher 

 has kindly undertaken. In the following table, which is ar- 

 ranged according to polar distance, the first column contains 

 the mean of observations made above and below the pole, the 

 same value having been given to both from the pole to u Auriga? 

 exclusive ; and from this star down to the horizon the value 

 of the lower passages having been diminished according to a 

 scale supplied by the observatories themselves. The remain- 

 ing four columns contain the differences of the determinations 

 obtained in the four different ways from the mean ones. 

 Vol. 64. No. 315. July 1824. C 



