32 The Microscope. 



quaintance with the Zeiss binocular eye-piece, and having 

 reason to believe that not one is to be found in California I can- 

 not comment upon it ; but the Wenham form is my every-day 

 companion. If "Amateur " has experienced " unpleasant strain 

 upon the eyes and weariness cifter long use," such statement 

 leads to the conclusion that he must be unfortunate in the in- 

 strument used. For the last ten years have taught the writer that 

 there is a very perceptible difference in the work of different 

 makers as relates to the binocular body-tubes. In 1880 I be- 

 came acquainted with a Crouch binocular of high grade. This 

 was regarded at tbe time as especially good ; but it was not easy 

 to obtain stereoscopic effect, and with some it was unattainable. 

 A younger brother of my own was one of such persons. Since then 

 the binoculars of Zentmayer (Histological) and of Beck have be- 

 come more or less familiar ; while for five years past I have 

 owned a Bausch and Lomb Universal binocular, which has proved 

 perfect in respect to freedom from strain upon the eyes and to 

 excellent stereoscopic effect. 



The first time that my brother alluded to, looked through this 

 " Universal " he exclaimed that now at last he had realized the 

 stereoscopic effect. 



The item in the workmanship which made all this difference 

 was simply that in my own instrument due provision is made 

 for approximating the eye-pieces near enough to suit all eyes. 

 When the axis of the oculars is adjusted to the observer's eyes, 

 prolonged use can be carried on comfortably and beyond the 

 range of a moncular. This, too, is really the main advantage 

 of the binocular; for there are those who care little for the stereo- 

 scopic effects, or who are prevented by some defect of eyesight 

 from realizing it. 



The matter may, for the presnt, be summed up somewhat as 

 follows. Advantages of the Wenham form : the simple swing- 

 ing of a prism to change into a monocular ; lower price, because 

 of less complicated construction ; capability of use with several 

 pairs of eye-pieces giving a range of magnifying powers ; saving 

 of weight and larger area of field. Advantages of the Abbe 

 binocular eye-piece : variety of effects produced ; availability 

 with any power ; avoidance of double body-tube ; lessened fa- 

 tigue(?) of observations. 



Even with the correction of the faults of the binocular eye- 

 piece, mentioned in "Amateur's " article, I believe there will 

 still be a place for the Wenham binocular. If the Abbe binocu- 

 lar is superior to the Wenham form it will make its own way, 

 and be welcomed by the writer as well as "Amateur " to the circle 

 of observing microscopists. 

 Benicia, Calif. Edward Gray, M. D. 



