NOTES 647 



simple instructions for adding, multiplying, etc., and also for converting 

 other fractions to octavals, accompany the rule. 



The following illustrates their simplicity in comparison with decimal 

 fractions, which have the disadvantage that each successive halving adds 

 a decimal place. % 



Vulgar. Octaval. Decimal. 



3 • • • • o3 '375 



A J 4 -l8 75 



7& 06 -09375 



s\ o°3 -046875 



The makers of this rule (Messrs. Watkins Meter Co., Hereford) issued 

 it in steel, 4 inches long, and have one 8 inches long almost ready. They 

 propose issuing in the same notation micrometers, gauge-blocks, and vernier 

 calipers for precision work, as they find this notation makes it possible to 

 mark and figure each division, which was not possible before with the much- 

 used binary fractions. For example, a calipers with the inch divided 

 into 8 numbered parts, and with a vernier scale with 8 numbered parts 

 occupying 7 of the |-inch divisions, not only reads down to 64ths with 

 large divisions, but the first figure of the octaval value is read directly on 

 the main scale, and the second figure on the vernier scale. It becomes easy 

 to construct micrometers with a separate scale for each place in the octaval 

 fraction. Advantage can also be taken of the perfection of a binary series 

 for addition. In a set of precision blocks or thickness gauges of an octaval 

 series, only three blocks (4, 2, 1) need be provided for each place of octavals, 

 as from these three figures, values from 1 to 7 can be made up ; there is 

 also the advantage that the value for each octaval place is taken from a 

 separate group of blocks, and the different places are never mixed up as in 

 decimal engineering measurements. The following is the complete set of 

 thickness gauge-blocks from which any measurements can be taken in 

 64ths ( oi) from *V to iff inch (i 77). 



I» o4> o 2 > o 1 ' o°4> o° 2 > o OI « 



For example, the value 1 if inch, which is i 36 in octavals, is made up with 

 blocks as follows : 1 for the integer, 2 and i for the first figure in the 

 fraction, and 04 and 02 for the second figure of the octaval fraction. 



The 3rd place in an octaval fraction is shs, and half of this being so near 

 the familiar thousandth of the mechanic makes the substitution of octavals 

 for decimals in the " limits " for fine mechanical work quite easy. 



It is only proposed to apply this notation to fractions of a unit. -"'All 

 to the left of the " pip/' that is all integers, remain in the ten grouping. 



The Institute of Physics. 



The need has long been felt for a corporate body analogous to the Institute 

 of Chemistry which could represent the profession and strengthen the 

 position of workers engaged in physics. The professional physicist is scarcely 

 recognised as such. During the war, in a certain Government Department, 

 when the need arose of appointing research workers in physics, it was found 

 necessary to style them research chemists. Probably the physicist himself 

 is to some extent responsible for this state of things. He has drifted toward 

 the academic rather than the technical side of his subject, and has left the 

 applied side to engineers on the one hand, and to chemists on the other. 

 The war has taught him that there are technical things with which he is 

 most qualified to deal, and he is now stirring himself to get his claims recog- 

 nised. 



Only the co-operative action of all physicists in the country will succeed 



