266 THE POPULAR SCIENCE MONTHLY, 



of the nebula and its contained stars. There was a large number of 

 errors in this catalogue, and Bond's work was sharply criticised by O. 

 Struve, whose "Memoir on the Nebula of Orion " appeared in 1862, 

 Struve's work, which was a revision and an extension of the work of 

 Liapanoff (done at Kazan with a 9-inch refractor), was executed 

 very carefully with the 15-inch telescope of Pulkova ; and some of 

 his strictures on the elder Bond's work were so severe as to induce 

 G. P. Bond, his son, then Director of Harvard College Observatory, 

 to take up his father's work, to complete and amend it. This he has 

 done in a most admirable monograph, which is a model of its kind. 

 We have already spoken of his engraving of the nebula, and its ex- 

 cellence is only commensurate with the completeness of the whole of 

 the memoir. 



Fig. 7 represents the small stars in the now familiar ground near 

 the trapezium. 



Fig. 7. 



S 



N 

 Nebula Orionis. (G. P. Bond, 1865.) 



It will be seen how much fuller this map is than Lassell's, which 

 contains more small stars probably than any of the preceding ones. 



Lord Rosse's great reflecting telescope of 6-feet aperture was em 

 ployed at various times, between 1848 and 1867, in making drawings 

 of the Orion nebula ; and we have, as the results of the work, two 

 great engravings, upon which much care has been spent. 



These certainly differ in many important points from the preceding 

 drawings which were made by reflectors (and experience will show us 

 that it is not easy, critically, to compare drawings made by reflectors 

 and by refractors) ; but this is simply a proof that the drawings of dif- 



