43'> TliKkllSTlUAL IMIVSICS. 



executed measurements of IMichelson'^ on the tidal oscillations 

 of a pair of short undergTound horizontal canals. These measure- 

 ments seem, of all hitherto made, to be most likely to lead 

 :o a trustworthy determination of earth-tides, and of earth rijg;id- 

 ity ; but it is essential that they should be re])eated at various 

 places and under a variety of local circumstances. As is well 

 known, the total effect observed arises from about six diiterent 

 though connected causes which have to be disentangled, and it 

 :s hig'hly desirable that the measurements should be made at 

 places well removed from the coast, so as to give the earth- 

 tide as nmch relative prominence as possible. Geoloi^jical sim- 

 ])licit}' of underground stratihcatiDU is also desirable. Both of 

 these conditions can, I imagine, be tolerably well fulfilled towards 

 the central parts of the Uninn. Unfortunatel}-, the method i> 

 expensive in respect both of time and money. On the other hand, 

 in regard to the mathematical and astronomical collaboration that 

 wotild be necessary, we might, 1 think, confidently rely on the 

 ])ractical sympathy of one of our members, the Astronomer 

 Royal, universally recognized as the g-reatest living authority on 

 :hc subject. 



The programme of research 1 have taken leave to suggest 

 may api^ear at once too ambitious and too j^artiak .\s regards 

 -■he latter ctMidition. 1 ha\e sim])ly noted a few things in which 

 I hajjpen to be personally interested. As reg'ards the former, 

 I l)eHeve that well-considered organization oi our available work- 

 tr<. inside and outside of the universities, on lines mutually agreed 

 • m. would enable us to attain results of no small importance. I 

 cannot think of any better method of setting such an oro^anization 

 on foot than through the formation of a Meteorological anrl Geo- 

 physical Committee of this section, for the direct business of 

 org^anization of research. Such a committee would meet an- 

 nually at the meetino- of this Association, to consider the jn'o- 

 gress of the previous year, ma]) out future work, get in touch 

 with fresh workers, and endeavour to secure the necessary tinan- 

 cial help from the State and from private benefactors. 



If the suggestion should i>rove fruitftil in regard to the 

 particular researches 1 have taken leave to note as desiralile, it 

 mi^ght readily be extended to the work of other sections. ( )nly, 

 T think it would be well that the available scientific strength of 

 any one section should not be dissipated on too many sul)jects 

 at the same time. 



(Read July 4, 1917.) 



Discussion. 



Mr. J. S. VAN DER LiNGEN : As a former pupil of Prof. 

 Morrison's, I gladly pay a tribute to the inspiration which he 

 gave to his classes. It was at his instigation that I started 

 certain work connected with the colour of the sky and allied 



* A. A. Aficholson. '' Ripidity of !*"arth." Journal of Cjcnlflf;y. 22 [2!, 

 97-1.?"- 



