A Simple Decimal Scale for Biological Work. 63 



IV. Oti a Simple Decimal Scale for Biological Work. 

 By J. G. GooDCHiLD, H.M. Geological Survey, F.G.S., 

 F.Z.S. 



(Kead 16th April 1902.) 



Those who are doing practical work in biology, or in other 

 departments of natural science, often require to make a 

 series of relative measurements relating to the different 

 parts of some object under consideration, and to state the 

 dimensions so obtained in the form of fractional lengths of 

 some part which has been selected as the unit of comparison. 

 The methods of craniometric measurement proposed by 

 Huxley in his well-known essay on the Canidse {Proc. 

 Zool. Soc, 1880, p. 238), afford typical examples of the kind 

 referred to. This method of comparative measurement has 

 long been in general use in connection with many other 

 branches of biological investigation, and no one who has 

 employed it can feel any doubt regarding its practical utility 

 But where a large series of measurements of such objects as 

 the skulls of some particular species have to be made, and 

 there happens to be much disparity in regard to the absolute 

 size of each of the individuals under examination, the 

 methods usually adopted are apt to prove somewhat un- 

 satisfactory, and their application requires a considerable 

 expenditure of labour and time. There is, therefore, need 

 for some improvements upon the mode of working usually 

 adopted. 



Similar requirements having arisen in connection with 

 some crystallographic work relating to Scottish Mineralogy, 

 I have been led to employ some methods of work which, after 

 having been put well to the test of practical application, 

 have been found to answer their purpose very well. A 

 short description of these methods may, therefore, be accept- 

 able to fellow-workers in science. 



The object in view may be stated thus : — Given a certain 

 line of variable length, chosen as a unit, to ascertain the 

 relative lengths of certain other dimensions, so as to be able 

 to state their proportions in relation to the unit chosen in 



