December 1 2th, igi6.\ PROCEEDINGS. xiii 



It will be found that the readings of Specific Gravity from 

 i.O to 2.0 occupy 30° of the scale, and the graduations between 

 i.o and about 3.0 are conveniently large and open, giving accurate 

 results. 



Above about 5.0, however, the graduations become much 

 closed up, and the balance is of no practical use. It is, how- 

 ever, particularly suitable for the determination of the Specific 

 Gravity of samples of rubber, which rarely rises above 2.5. 



It may be shown, also, that exact counterpoise to the hori- 

 zontal in the first adjustment is by no means necessary, since 

 an error of 5° or 10° from the horizontal hardly affects the 

 subsequent reading. This is very convenient where an economy 

 of time is important. In fact, the chief advantage of such an 

 appliance is the speed with which a large number of determina- 

 tions can be made. 



Professor W. W. Haldane Gee, B.Sc, M.Sc, Tech., made 

 a short communication on a simple method for converting de- 

 grees Fahrenheit intO' degrees Centigrade, and back again from 

 C. to F. 



Professor HORACE Lamb, M.A., LL.D., Sc.D., F.R.S., read 

 a paper entitled "The Deflection of the Vertical by Tidal 

 Loading of the Earth's Surface." 



The paper gave an account of some investigations in the 

 theory of elasticity bearing on the above subject. The observa- 

 tions of Hecker, Orloff, and Michelson on lunar deflection of 

 gravity exhibit an inconsistency between the results for the 

 E.-W. and N.-S directions respectively. This has been 

 attributed to the attraction of the tides, which have the same 

 periodicity as the direct lunar influence, and to the tilting which 

 their varying pressure produces in the solid earth. Some 

 calculations illustrative of the effect which the tides might pro- 

 duce in this way have recently been made, but various 

 modifying influences have been left out of account. The author 

 had attempted to make an estimate of these corrections. 

 Though of slight amount in many cases, they may under 

 certain conditions attain considerable relative importance, Their 

 general effect is to diminish the deflections as calculated on 

 previous theories. 



Professor Haldane Gee, Mr. W. G. Pemberton, Mr. W. D. 

 Evans and other members took part in the discussion which 

 followed this paper. 



