OBJECTIVES OF LOWER BALSAM ANGLE. 147 



get better shows than was the case with the former ob- 

 jective, and on applying the one-quarter eye-piece I 

 have better definition yet. There is some loss of light, 

 to be sure, but there is enough left to do the work, and 

 in a more satisfactory manner than occurred when the 

 lower eye-piece was in position. I take this case as an 

 illustrative one, because I have used it repeatedly with 

 my visitors, and the demonstration has, 1 believe, 

 always been accepted as satisfactory. It will be noticed 

 that thus using the two- thirds, the power applied at 

 the eye-piece was greater than the rating of the objec- 

 tive employed, and a tolerable test for an object-glass of 

 such low nominal power. We have here, then, in the 

 experiment cited, an illustration of what may be said 

 to be k< power to bear high eye-piecing." 



There is a general and indefinite idea afloat, that 

 there is something about high eye-piecing which ought 

 to be condemned. Without making any special attack, 

 it ir ay be admitted that observers "came honestly by 

 it." The facts warrant this much: powder z. e., ampli- 

 fication or magnification when not wanted, is to be 

 condemned, and it matters not how obtained, whether 

 at one end of the tube or the other. On the contrary, 

 if any thing valuable is to be obtained by amplification, 

 then we are auth orized to use it, and to the best advan- 

 tage apply it at either end of the tube, as the case may 

 warrant. There seems no more propriety in the con- 

 demnation of high eye-piecing per se than ought to ob- 

 tain in the use of objectives of short focal length. 



