57 



Mr. Lowne quite concurred with Mr. Stewart ; as to the eflFects in both eases, 

 it, of course, amounted to the same thing, whether the eye was closed or whether 

 it was not used, and there could be no doubt but that it greatly relieved the eyes 

 to have both open when working with a microscope having a single tube. There 

 were two things which might happen when drawing with botli eyes — it might 

 happen that both eyes would be converged upon the same object at the same 

 angle, but it would more usually be done by a squint. There was another 

 thing which also occurred to him, namely, that the foci of the two eyes would 

 have to be different, and this would be sure to cause very great fatigue to the 

 eyes. Their axes must, of course, convei'ge, they could not possibly be parallel, 

 and the question was at what angles did they converge ? 



Mr. Tafe remarked that there was a convergence of the eyes both in looking 

 through a microscope and in reading a book, and asked whether there was any 

 difference between the two cases ? 



Dr. Sansom said there could be no doubt but that there was a difference 

 between the convergence of the eyes in drawing as described, and in reading — 

 in the former case the axis of the eye would be a right line, or, rather, the 

 perpendicular line of a right angled triangle, whilst that of the other eye would 

 be its hypotheneuse ; and this would not be the case in reading a book. 



Mr. Mainworth inquired whether there would be some 'variation according to 

 the power used ? 



The Chairman thought there might be a little. 



Mr. Tafe asked whether the angle at which objects were seen would not render 

 the binocular microscope injurious to the eyes ? 



Dr. Sansom said that the angle would be so slight when using the binocular 

 that it amounted to practically nothing. 



Mr. E. P. Williams said that if he looked at the image through the neutral 

 tint reflector, and then took it away and substituted an opaque reflector, then 

 when he examined the image on the paper he could not see that there was any 

 difference in the angle ; and he could not see that he squinted at all. He might 

 also mention that once he introduced a piece of paper on the stage of tbe 

 microscope where he could see it with the non-observing eye, and he drew the 

 object in this way. 



Mr. Mclntire said that this was the method which he generally adopted in 

 drawing objects, but he was quite conscious that in doing so he squinted. 



Mr. Lowne said that as some gentlemen did not seem to understand what 

 squinting was he would just explain it, for be was sorry there should be any 

 misapprehension. It was squinting when two objects were seen under such an 

 angle of convergence as to make them overlap, as described by one speaker, — 

 squinting was when one eye looked straightforward and the other looked at an 

 angle either inward or outward. With regard to drawing upon the stage of the 

 microscope, he had often done it, but should certainly do it no more, because it 

 could not be done without a squint, and he could not squint without injuring the 

 eyes. In looking through the binocular microscope the angle was really very 

 little indeed, because the image was not seen by looking ^A,o?(^A the object- 

 glass, but only at a picture in the eye-piece of the microscope. It must not be 

 thought that a person looked down the tubes through the object glass, for if 

 this was the case the binocular microscope would be a very painful institution, 

 and would very speedily have to be put out of use. 



Mr. R. P. Williams said that he did not regard it as a squint at all. 



Mr. Lowue was sorry anyone should go away with a wrong impression, but 



