70 Notices respecting New Books. 



terrestrial longitudes. The room is eighteen feet by twelve, sixteen 



feet in height outside, and ten feet five inches inside, and has a flat 

 and well-leaded roof. The stone piers, six feet high, and cut from 

 a single block of Portland stone, are erected on a brick foundation 

 resting on the " live " rock, and the flooring of the room is carried 

 so as not to touch them. The transit- clock, by Vulliamy, has two 

 peculiarities suggested by Captain Smyth : the steel rod of the pen- 

 dulum is immersed six inches in the mercury, that both may be 

 simultaneously afi^ected by changes of temperature ; and the clock- 

 weight consists of separate cylindrical pieces, by which the moving 

 force may be adjusted so as to produce any required arc of -vibration. 

 Two meridian marks (mounted, characteristically of our author's 

 antiquarian predilections, one on a representation of the temple of 

 Janus, the other on a miniature of the facade of the Temple of Con- 

 cord at Girgenti) are placed respectively at the distance of one hun- 

 dred feet north and south of the obsers^atory slit, and by the inter- 

 vention of two lenses of one hundred feet focal length fixed in the 

 window-sills, are viewed by parallel rays entering the transit tele- 

 scope. This meridian appliance, the theory of which (as we gather 

 from the statement at the top of page 236) was suggested to the 

 author by Baron de Zach, has the great advantage of enabling the 

 observer to ascertain at all times the error of collimation of his tele- 

 scope, without waiting, as in the use of a distant meridian mark, for 

 a favourable state of the atmosphere. The method of two collima- 

 tors looking into each other, which is that now employed at Green- 

 wich, involves the same principle, and has the further advantage of 

 not even requiring a reversion of the transit. 



Three years after building the transit-room, Dr. Lee determined 

 upon enlarging his astronomical means by the addition of an equa- 

 torial. Under Mr. May's able engineering, a tower, solidly built, 

 and of fifteen feet interior diameter, was surmounted by a hemisphe- 

 rical dome, covered with copper sheathing, moveable on three cannon- 

 balls, and opening by a single shutter extending from the zenith to 

 the wall-plate. After some delay, occasioned by the object-glass 

 purchased for the equatorial being pronounced by Mr. DoUond to 

 be unworthy of a costly mounting, it was arranged that the telescope 

 employed by Captain Smyth in making the observations recorded in 

 his " Cycle of Celestial Objects," being no longer in use, should be 

 transferred from Bedford to the Hartwell Observatory. The object- 

 glass, one of Tulley's best, is 5'9 inches in diameter, and of 8 feet 

 8^ inches focal length. The equatorial is mounted in a very simple 

 manner, has hour and declination circles each 3 feet in diameter, and 

 is moved by clock-work. 



The meridional observations taken by Mr. Epps, late Assistant- 

 secretary of the Royal Astronomical Society, were begun in the 

 early part of 1838 and continued to August 1839, when they were 

 interrupted by the death of the observer. The observations of 315 

 of the stars, many of them taken with the moon, are discussed by 

 Captain Smyth, and absolute right ascensions deduced from them 

 are compared (pp. 256-283) with the Astronomical Society's Cata- 



