ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 505 



Quekett Microscopical Club. — The 449th Ordinary Meeting was 

 held on June 19, the President, Prof. E. A. Minchin, M.A., F.Z.S., in 

 the Chair. Mr. A. Earland exhibited and described a number of pre- 

 parations of Foraminifera, in regard to which special reference may be 

 made to a slide showing " triple isomorphism." The species were 

 Cornuspira of the Porcellanous type, Ammodiscm of the Arenaceous 

 group, and Spirillina, a Hyaline form. Mr. W. Wesche, F.R.M.S., con- 

 tributed a paper on " The Proboscis of the Blow-fly, Calliphora erythro- 

 cephala Mg. : a Study in Evolution." 



Ciceri Smith's Direct-reading Micrometer-gauge for Cover-glass. 

 At the March Meeting J. Ciceri Smith exhibited and gave the follow- 

 ing description of a direct-reading micrometer-gauge (figs. 132 and 133). 



" The difficulty of reading a micrometer of the indirect type in a dull 

 light is a well known fact, and as a short mental calculation is usually 

 required to arrive at the proper result, an error is very liable to slip in, 

 especially when the instrument is only used occasionally, or when the 

 small graduations are indistinct. 



" The improved instrument is of the caliper type, with the addition 

 of a set of self -calculating or indicating dials, the chief feature being 

 that the readings are seen at a glance. They are made in various sizes, 

 from the smallest up to those of 1-in. capacity. I shall, however, confine 

 my description to the smallest size, as this is the pattern which is best 

 suited for the measuring of microscopical glass. 



" The readings for this small work are indicated on two dials ; the 

 first figure (reading from the left) indicates hundredths, and the second 

 figure thousandths of an inch, which latter is our British unit measure- 

 ment, so that one-thousandth of an inch is technically known as ' one 

 mil ' — therefore these units for conciseness are frequently described as 

 'mils.' The divisions on the bevelled edge of the thimble indicate 

 | mils. I may mention that the divisions on the shank are for larger 

 measurements, and indicate tenths of an inch — capacity ■£$. 



" The gauge consists of a horseshoe-frame, having a screwed shank 

 or fixed nut to carry the micrometer spindle, and a recessed portion to 

 receive or contain the mechanism, which is in turn covered by metal 

 plates. The front plate is pierced with apertures, through which the 

 figures appear consecutively. 



" Two principles are involved in the construction : — (1) A screwed 

 spindle travelling in a fixed nut and fitted into the body of the frame ; 

 (2) working in conjunction with, and operated by the micrometer spindle 

 is the registering mechanism. When the instrument is manipulated so 

 as to increase the gauge the counter moves forward, and if manipulated 

 so as to decrease the gauge the counter moves backward. 



"The recording mechanism is self-contained in an independent, 

 cage-like frame, and is operated in the following manner : — The decimal 

 figures appearing in bold relief on the index are automatically indicated 

 in a step-by-step motion, actuated by the rotation of the micrometer 

 spindle, which in turn drives a train of pinion-wheels and a cam-wheel, 

 and upon the arbors are mounted white collars or dials, having black 

 figures on their periphery. On the micrometer spindle is fitted a 



