184 Mr. T. H. Blakesley on some Facts connected with 



and that interval would be 'SG^ of a second, which number 

 happens to be the square root of -746; and this would give us a 

 coincidence in magnetic field, whose formula is v~^ t~^ p^. But 

 magnetic field is not a magnitude of which we keep instru- 

 mental standards, as we are wont to do of resistance, capacity, 

 mass, time, length, and sometimes of E.M.F. 



It will be observed that in the formulae the symbol of power 

 occurs either simply or raised to the power of ^, and we may 

 bring power into decimal relation with horse-power either by 

 taking •746 of the unit or 7'46. The square roots of these 

 relations are -86373 and 2-73136. Using the latter number 

 we should obtain no further coincidences among the mag- 

 nitudes. 



In reviewing the results indicated by the above calcu- 

 lations, in dealing with the units of science in such a way as 

 to obtain : — 



(1) The correlation of the thermometer ; 



(2) The unity of the two systems, Electrostatic and Elec- 

 tromagnetic ; 



(3) The bringing of the unit of power into decimal relation 

 with the horse-power ; 



I come to the conclusion: — 



(1) The thermometer Centigrade may be brought into 

 decimal relation with temperature-units on the O.G.S. system 

 or quadrant-volt-second system by adopting the specific heat 

 of air at constant pressure as unity. 



(2) That such decimal relation is compatible with a change 

 in the unit of power to j f/oo of 1 H.P., which latter change 

 could take place without changes in the units of time, length, 

 velocity, resistance, and capacity, but would involve a change 

 in the important standards of mass. 



(3) That the union of the two electrical systems could be 

 brought about in the simplest way by taking ^ of one 

 second as the unit of time ; such a change retaining the 

 gramme-boxes, and the metre decimally, and the coulomb, 

 but requiring the unit of capacity to be qIq of 1 farad and 

 the unit of resistance to be 30 ohms. 



To my mind the last change recommends itself. No real 

 change would be necessary in the face of the chronometer, or 

 in the metre, or in the gramme-boxes. Each microfarad 

 would have to be called -0009, and each second 30, and every 

 30 ohms 1 unit. A habit has arisen of attaching particular 

 names to units. This, without doing very much good, adds 

 greatly to the stability of the unit, and makes any subsequent 

 change so much the more difficult. The practice has almost 

 always been confined to electi'icians, somewhat too oblivious 

 of the mechanical basis of a proper system. 



