Notices respecting New Books. 71 



logue, for the sake of testing their trustworthiness in the determi- 

 nation of longitudes, the object to which the observations were pri- 

 marily intended to be applied. In fact, while absolute determina- 

 tions of celestial positions can only be effectively made in large public 

 astronomical establishments, the means of private observatories may 

 be most usefully employed in differential observations, in which class 

 moon-culminations, Umited to the appUcation just mentioned, are to 

 be included. In 1842 the observatory was trigonometrically con- 

 nected by Captain Smyth, and his son Henry Augustus, of the Royal 

 Artillery, with Aylesbury church-spire, and by inference from the 

 great Trigonometrical Survey, its longitude was found to be 

 3m 22=- 63 west of Greenwich, and its latitude 51° 48' 14"- 6 north. 

 There appear to be ample means of verifying by independent astro- 

 nomical observations the assumed position of Aylesbury Church, as 

 no fewer than three observatories furnished with transit-instru- 

 ments, in addition to that of Hartwell, exist in the immediate neigh- 

 bourhood ; Mr. Dell's, already mentioned, one erected by the Rev. 

 J. B. Reade at Stone, and another by the Rev. C. Lowndes at the 

 Hartwell Rectory. 



The measures of double stars (pp. 287-290) were taken with the 

 equatorial of the Hartwell Observatory, the instrument being obli- 

 gingly kept in readiness by Dr. Lee for the immediate and particular 

 service of its former possessor. They are re-examinations of objects 

 enrolled in the Celestial Cycle, and being made by the same observer 

 and the same instrumental means, are strictly comparable with the 

 measures recorded in that work. 



Captain Smyth has paid particular attention to the colours of double 

 stars. In the work before us we are presented with a comparison, 

 probably the first of the kind, of two independent series of observa- 

 tions of this class. It appears that the Bedford Catalogue, in which 

 such colours are assigned to all the objects as struck the observer 

 at the time of observation, reached the hands of Signor Benedict 

 Sestini of Rome, after he had been engaged on a very extensive 

 series of observations of the colours of stars in general, and led him 

 to form a table of comparisons of his own estimates with those of 

 Captam Smyth on double- stars. The conclusions he had already 

 arrived at, which for their interest deserve to be mentioned here, 

 were, that " of 2540 stars (those of Rally's Catalogue observed at 

 Rome) the yellow stars are about half the total number, and equally 

 distributed ; the white stars are one- fifth in scattered portions ; and 

 the orange rather more than one-fifth. The red and the blue are 

 rare from the pole to 30° of north declination ; the blue then become 

 numerous (=y) to the equator, especially from jR. 18^ to 20'' ; 

 and the red abound from 0'' to 30° south declination, and JR. 16'' 

 to 20''." But it would seem, when the result of the above-men- 

 tioned chromatic comparison is taken into account, that such con- 

 clusions require for their estalilishment the collective observations 

 of different observers in different circumstances. Pages 293-298 

 contain a table of the colours assigned to the components of 109 of 

 the brighter double-stars by Smyth in the years 1831-43, by Ses- 



