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of the -Jy inch graduations, and that the fourth mark of the vernier was coin- 

 cident with a mark on the scale above, the reading being, therefore, '0Q4; 

 inch; and proceeding in the same way with the adjoining scale, the reading 

 was found to be 1'62 mm. It was pointed out in further illustration of the 

 ingenuity of the invention that on the reverse side of the instrument there 

 was another scale by means of which the sectional area of a round wire was 

 shown in thousandths of a square inch, and this value would enable the 

 electrician to readily determine the weight per 100ft., the resistance, and 

 the quantity of current which the wire would safely carry. 



The communication was illustrated by a diagram, and by the exhibition 

 of the patent gauge, together with a standard micrometer rule, divided to 

 64ths and lOOths in. ; and also one of the ordinary wire gauges by way of 

 comparison. 



The Chairman said the contrast between the two gauges was certainly 

 very great, and he could not sufficiently admire the mechanism of the little 

 apparatus before them. 



Mr. Hardy had often thought that the fine adjustment of the microscope 

 might generally be used for measuring the thickness of cover glasses. If the 

 screws were always made 50 threads to the inch, then, by focussing at the 

 top and bottom of a cover glass, it would be easy to ascertain by a certain 

 movement exactly the thickness. He had done this roughly himself, but he 

 believed his fine adjustment was at the rate of 60 turns to the inch. 



Mr. Hailes said that Smith and Beck always graduated the milled head 

 of their fine adjustment for the very purpose of measuring depth, and had 

 supplied directions in their book to instruct the purchasers how to use it. 



The Chairman said that Powell and Lealand also always graduated the 

 heads of their fine adjustments for the purpose of measuring depth. 



Mr. Karop said there were many other things made for the purpose of 

 measuring thickness, and although no doubt this gauge might be very useful 

 for some things, he thought thin glass would be very apt to get broken. 

 Zeiss made an instrument especially for the purpose of measuring thin 

 cover glasses. Then there was the old lever of contact; and some time ago 

 a little thing was shown there by Mr. Hensoldt for a similar purpose. The 

 gauge exhibited was no doubt more useful to the engineer. 



Mr. Hailes said that the gauge shown by Mr. Hensoldt was the ordinary 

 gauge used for measuring pianoforte wire. 



The Chairman said that some years ago he showed what he called a caliper 

 eyepiece, which was a modification of the indicator by Qnekett, but each 

 finger-point was curved and was moved by a tangent screw. All that was 

 needed, therefore, was to take up the cover glass with the stage forceps, 

 and to fit its edge into this optical gauge under the microscope. 



He also wished to draw attention to a matter which had been under 

 consideration by the Committee, and which they wished to bring before tho 

 members of the Club. Members were no doubt aware that it had often 

 happened lately, when the date of a meeting came round they were without 

 a paper, and to meet the inconvenience of this state of things the Committee 

 proposed, if possible, either by notice or agreement, to arrange for some 



