654 REPORT — 1897. 



tenths of a ton of the whole oxygen of the atmosphere resting on Great Britain. 

 The Commission estimated fifty-six thousand million tons more of coal as probably 

 existing at present in lower and less easily accessible strata. It may therefore be 

 considered as almost quite certain that Great Britain could not burn all its own 

 coal with its own air, and therefore that the coal of Britain is considerably in 

 excess of fuel supply of rest of world reckoned per equal areas, whether of land or 

 sea. 



5. A Canadian and Imj^erial Hydror/raphic Survey. By Alexander 

 Johnson, M.A., LL.D., Professor of Mathematics, Fice- Princijjal, 

 McGill University. 



In 1884, at the Montreal meeting of the Association, a paper was submitted to 

 Section A by the present writer, in consequence of which a Committee was 

 appointed for the ' Promotion of Tidal Observations in Canada.' The writer was 

 made Secretary, and subsequently Chairman. This Committee, supported by the 

 Royal Society of Canada and by those specially interested in navigation, succeeded, 

 after many delays, in getting the Canadian Government, in 1890, to make a grant 

 for tidal observations, which were to include, not only the rise and fall of tide, but 

 also the tidal currents. The grant was continued from that time until the present 

 year, when it was reduced, so that the survey of the currents could not be con- 

 tinued this summer, although an investigation of the utmost importance for the 

 navigation of the St. Lawrence, more especially when the ' fast Atlantic Line ' ia 

 going to be established. Possibly the entire grant is imperilled. 



It is believed that this reduction would probably not have taken place had 

 there been in existence a fully organised Hydrographic Survey for Canada to 

 advise the Government. The lioyal Society of Canada had some time ago recom- 

 mended the creation of such a department, and at its recent meeting in Halifax 

 appointed a deputation to present its views to the Government. 



The work of such a department can probably be most effectively canied out 

 with the co-operation of the Admiralty. 



The object of the present communication is to seek the advice and aid of the 

 British Association in inducing the Imperial and Canadian Governments to act 

 together in making the necessary arrangements, which, if found satisfactory, might 

 possibly be extended to other colonies, and thus the basis of an ' Imperial Hydro- 

 gi-aphic Survey ' might be laid. 



6. On the Specif c Heat of Superheated Steam. 

 By Professor J. A. Ewing, F.R.S., and Professor Stanley Dunkeeley. 



The authors measure the amount of heat required to beat steam above its tem- 

 perature of saturation by allowing dry saturated steam to pass through a porous 

 plug and observing its temperature and pressure before and immediately after the 

 passage. The total heat of the steam before passing the plug is known from the 

 experiments of Regnault, and this is equal to the total heat of saturated steam at 

 the pressure beyond the plug plus the amount of heat required to heat steam at 

 that (constant) pressure from the temperature of saturation up to the observed 

 temperature. Hence the second of these two quantities of heat is found. In pre- 

 liminary experiments the pressure beyond the plug was atmospheric, and the 

 observations consequently related to the superheating of steam under atmospheric 

 pressure. The experiments have not yet been carried far enough to determine 

 with certainty what happens during the very first stages of superheating, but it 

 appears from the preliminary observations that the mean specific heat for the first 

 ten degrees of superheating is less than the mean specific heat for larger amounts 

 of superheating. At higher temperatures of superheating under this pressure the 

 specific heat approximates to the value 048, as determined in the direct measure- 



