Chemistry and Physics. 



;housandths of 



a milli 



meter in 



the disl 





:e hetweei 



1 the 





i iiu 



narked on the 



tube.- 



■ Compte 



s Rendu 











0. Film* of 



\V.,t,<>- 



.—Mr. ' 



rxLOR r 



■■ad 





■ tli( 



\ U 



Ion Physical Si 



f K y. 



on the c 







capillary 







till 



The author endeavc 

 eliminate the action of all forces except that of gravity by i 

 merging his " valves" in water. The models which he exhibit 



li a piston.' whi, 

 iapable of lifting by cohe; " 



Of 111. 



Jtal, the 



natur 



e of the surfaces 



in contact differing in 



i the sev- 



oral 







Fro 







m he c 



oncludes 



that 



the titn 



e d.iri 



n S 







n be si 







Kb. Upoi 



i the - 



ize of the surfac 



e of contact, 



■ 



>rence of 



press. 



-ire within an 



d v. 





moving parts, 









of the < 



valve. 



Oi 



i the contra _ 



ry, dry bodie 



s, such 



as Whit- 



worri 



i's surfs 



.co pi: 





, will adhere "for an indent 





od. Mr. 



Tylo, 





■rs tlia 



t th 



b supporting 



of a body in 





due to a 



.lifter 



ence of 



pressu 





i the water i 



tself and he a 



dduced Giffa 





orassh 





tha 







He has 



also 



■ 



the fc 





of a drop oi 











when a 



fly walks 



on a ceilin 







the same 



maim 



er as th 



eheav 



y valves in the t 



nodels exhibit. 



ed.— JVa 



t»re, xv, 



10. Fog- Signals.— Prof. Henry at the recent meeting of the 

 United States National Academy communicated some additional 

 ted and elaborate researches con- 

 cerning sound in relation to fog-signals. His principal investiga- 

 tion this year had reference to the divergence of sound, especially 

 as to the phenomenon kt i .n,, is t Oceai Echo fo test the ex- 

 planation given by Prof. Tyndall. "i from the 

 :i »-. the trumpet of a siren was turned directly to the zenith. The 

 blast was exceedingly- intense, but no echo was heard from the 

 'ion of the axis of the trumpet, i. e., from the zenith. 

 A loud echo was, however, hear. 1 , from the whole circumference 

 of the horiz. . m on land, the other half on water. 

 This was repeated man \ iiu -. ad » .-with the same result. 

 In one case a small cloud passed directiv across the zenith, from 

 t<-w drops of rain fell into the mouth of the trumpet; 

 st '! no sound was heard from the zenith, although sound con- 

 be heard from around the horizon. In this case on ac- 

 count of the divergence of the sound, portions of waves in every 

 direction must have descended to the horizon, and as some of 

 these must have reached the plane of the ocean in a path curv- 

 toward the s.-mree of sound, they would, when they 

 reached the ear of the ob- net th emu tt - < seem 

 as if coming from a point in the horizon, and hence would give 

 nse to the phenomenon of the 

 terent distances from the ear ( 



