336 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



Appendix. 



A New Fish-measuring Board. 



At the commencement of our herring measurements we 

 were confronted by the difficulty that there was no apparatus 

 suitable for rapidly and accurately making measurements of 

 fish to the nearest millimetre. None of the boards actually 

 in use could be used to measure more accurately than to 

 half a centimetre, and any form of calliper is slow in use, 

 even if accurate. Another objection to callipers is that the 

 points are often so blunt that it is difficult to adjust them 

 sharply to the desired point upon the body of the fish. 



It was to meet this need that this new board has been 

 designed. It has been elaborated from our ideas and manu- 

 factured by Mr. Pye, Mechanician to the Physics Department 

 in the University of Liverpool. 



The actual board is of the usual pattern. Across one 

 end is a wooden stop, against which is placed the extremity 

 of the fish on which the measurements are to be made, the 

 body of the fish being kept parallel to the edge of the board. 



Along one edge of the board is inserted a boxwood scale, 

 graduated in centimetres and millimetres. Parallel to this, 

 and bracketed to the edge of the board, is a stout brass rod, 

 square in section, running almost the whole length of the board. 

 Along this rod travels the actual measuring apparatus. 

 Fig. 1 shows part of the board, with the scale, rod, and 

 measuring apparatus. 



A separate view of the latter, on a larger scale, is given 

 in fig. 2. The base of this apparatus consists of a square 

 tube, which fits the brass rod attached to the board, and is 

 held in position by a pair of flat springs (shown dearly in 

 fig. 1) pressing against the rod. 



