202 



NATURE 



{Jan. 4, 1877 



The Great Nebula of Orion was the other chief object 

 of the observatory up to the death, in 1849, of Prof. W. C. 

 Bond, the father, and thence to the death of the son, 

 Prof G. P. Bond, in 1865. The observations of this con- 

 stellation form the latest as yet published volume of the 

 "Annals," issued, in 1867, under the supervision of Prof. 

 T. H. Safiford, then director of Dearborn Observatory, 

 but formerly in charge at Harvard as assistant in the 

 observatory. For Mr. G. P. Bond's work, and especially 

 for his observations on Uonati's comet, he received a gold 

 medal from the Royal Astronomical Society in 1865.^ 



Since the year 1866, in which the present director. 

 Prof. Joseph Winlock, took charge of the observatory, its 

 work has been yet further most successfully extended into 

 new fields of research, by his own labours, and those of 

 his able assistants, Messrs. Searle, Rogers, and Peirce. 

 Besides what is known as routine work of all observatories, 



Fig. 3. — Ground plan of Cambridge Observatory. A, west equatorial ; B, 

 library; C, computing-room; D, west transit; E. new piers for new 

 transit circle ; F, colHmator piers ; G, east equatorial ; H, giand en- 

 trance and stairs to east equatorial ; 1, prime vertical room and north 

 clock ; K, east transit ; L, south clock ; M, east clock ; N, Chrono- 

 graph ; O, anemometer register ; P, director's house ; Q, front door ; 

 K, magnetic obsetvatory ; S, rain-gauge ; T, anemometer. 



spectroscopic observations of the sun and of stars and 

 nebulae, and the most careful photographs of the sun, 

 have been frequent. Five hundred drawings of the sun 

 were made between January 1872 and November 1873, 

 and 500 careful drawings of solar prominences in the year 

 1873. To this work is to be added a great deal of labour 

 given to the determination of longitude differences, and 

 the observations, by Prof. Winlock, of the solar eclipse of 

 1869, at Shelbyville, Kentucky, and that of 1870, at Jerez, 

 in Spain. The general reader, as well as the astronomer, 

 cannot fail to be interested in the beautiful pictorial re- 

 presentations of these and of other astronomical pheno- 

 mena which have been issued by subscription recently 

 from Harvard. 



' Mr. Bond was the first American, we believe, to be thus honoured with 

 the gold medal ofa foreign scientific society. Prof. Watson, of Ann Arbor, 

 and more recently Prot. Simon Newcomb, of the United States Naval 

 Observatory, have been the recipients of like honours ; the former from the 

 Imperial Academy at Paris, the latter last year, from the Royal Astronomical 

 Society of London. 



The great equatorial, made in 1847 by Merz and Mah- 

 ler, of Munich, has an object-glass of 15 in. in diameter, 

 and a focal length of 22 ft. 6 in. The power of its eye- 

 piece ranges from 100 to 2,000; the hour-circle is 18 in. 

 m diameter. The movable portion of the well-balanced 

 instrument is estimated at three tons. Its original cost 

 was about $20,000. The sidereal motion given to this 

 telescope is now secured by clockwork from Alvan Clark, 

 which is spoken of by the observers as the only known 

 " driving-clock working with perfect steadiness." The 

 telescope rests on a central granite pier, in constructing 

 which 500 tons of granite were used. It is 40 ft. high, and 

 rests on a wide foundation of grouting 26 ft. below the 

 ground surface. Upon the top of the pier is laid a cir- 

 cular cap-stone 10 ft. in diameter, on which is the granite 

 block, 10 ft. high, bearing the metallic bed-plate. This 

 instrument is in the central " Sears Tower." 



The meridian circle was mounted in the west transit- 



FiG. 4. — Cambridge Meridian Circle. 



room in 1870. It has modifications, introduced by Prof. 

 Winlock, not usually found in transit instruments, chiefly, 

 that the graduated circles are directly above the piers, the 

 bearings of the pivots being carried by iron standards ; 

 the axis friction rollers rest on rods rising from the base 

 of the piers and counterpoised below the floor. The pivot 

 circles and reading microscopes are protected by glass 

 casing ; the object-glasses of the transit and of each of 

 its collimators, made by Clark, are each 8 in. 



In the west dome is another Clark equatorial, made in 

 1870, with an object-glass of 5^ in. In the east wing is 

 the transit circle made in Prof. Bond's directorship, by j 

 Simms, of London. Its focal length is 65 in., its object- 

 glass if\ in. ; its circles are 4 ft. in diameter, read byj 

 eight microscopes to single seconds. Cambridge pos- 

 sesses a number of more modern instruments, constructed | 

 to meet the wants of astronomical investigations at this j 

 day. 



The spectroscopes, photometers, and photographic ap- 

 paratus are peculiar in form and power. The spectre- ' 



