THE MICROSCOPE. 131 



woods, had shown three sets of lines on it, when other glasses of 

 equal powers, made by the first English opticians, had entirely failed 

 to define them." 



This test, named after Mr. Spencer, was sent to him by Prof. 

 Bailey, who doubted whether he could make a glass that would show 

 the longitudinal markings, as Ross's objective in Prof. Bailey's 

 hands could show them. Spencer applied the test to one of his ob- 

 jectives, and found not simply the longitudinal lines, but also, as 

 Queckett says, " lines which are in reality dots, and arranged so as 

 to exhibit both transverse, longitudinal, and even oblique striae." 

 With great surprise and admiration Prof. Bailey admitted the won- 

 derful discovery, and the test well bears the name in memory of it. 

 Mr. Spencer was the first, also, to resolve the markings on the 

 Graviatophora Subtilissiina. 



At this time Spencer's attention was given to a careful theo- 

 retical and practical examination of the truth of the published state- 

 ment that " 135° is the largest angular pencil that can be passed 

 through a microscopic object glass." This statement of Mr. Ross's 

 was soon proved incorrect by the production of a J^- ''^- objective, 

 having an angle of 146°. This must be regarded as Spencer's first 

 great triumph. It was followed by an increase of the angle of all 

 the higher powers, until in 1851 he made a 4-^ of "as near 180° as 

 can be obtained." We have taken some care to ascertain the 

 truth of the following statement, and we have every reason to believe 

 it is correct, viz., that this identical Jg is now in our possession. 

 It was purchased by Prof. Alexander Winchell in 1S55, and exhibited 

 by him before the American association for the advancement of .sci- 

 ence, which met in Albany in 1856, and by the experts there as- 

 sembled declared to be the finest objective in this countr}'. When 

 this glass came into our possession a number of years ago, it was 

 found to show a crack running across about Yi of the field. Upon 

 returning it to Mr. Spencer, he declared that he could make a new 

 one nearly as cheap as he could remedy this, "for it is one 

 of my first glasses * * * " he said, and the formula was so 

 different, and the injury so bad, that he returned the glass, and 

 took an order for a ^. Two-thirds the field of this Jg- will show 

 nearly as clear and distinct an image to-day as his more recent Jj. 



In 1843 Hamilton College conferred upon him the degree of 

 Master of Arts. 



