100 ANNUAL KECOKD OF SCIENCE AND INDUSTRY. 



as is practicable, of the physical properties of gases that find 

 their grandest exemplification in the atmosphere. 



The second volume of Lord Rayleigh's " Theory of Sound " 

 lias been published, and a third is promised. This work con- 

 tains a discussion by the master-hand of the theory of sound 

 in air, the mechanics of fluids, the influence of viscosity or 

 fluid friction, etc. 



The mathematical theory of the resistances and motions 

 of fluids is of such difficulty that only rarely do we have oc- 

 casion to note any real progress in our knowledge of this 

 subject. A valuable article on the resistance of fluids has, 

 however, been published by Lord Rayleigh {Philosophi- 

 cal Magazine), in which many important results are given, 

 with some account of the processes by which he arrived at 

 them. The expression for the resistance of a meteor or 

 other rapidly moving body will interest meteorologists. In 

 a subsequent note Lord Rayleigh discusses the subject of 

 the Vena Contracta. 



A large collection of formula? and data relative to the 

 movement of air in pneumatic tubes is contained in a series 

 of papers on this subject by Culley, Sabine, Bontemps, Un- 

 win, etc., in Vol. XLIII. of the Proceedings of the Institute 

 of Civil Engineers. 



Of mechanical problems whose solution offers something of 

 interest to meteorologists, we note the papers on Vortex Mo- 

 tion and on Waves presented to the London Mathematical 

 Society at their meeting on the Sth of November. In the 

 former paper Professor Clifford gives a simple solution of 

 the problem so profoundly handled by Stokes, Rankine, and 

 Ilelmholtz. The paper on Waves, by Lord Rayleigh, commu- 

 nicated some results, also published in his work on "Sound:" 

 the phenomena attending the advance of a group of waves 

 into still water, and those attending a group of deep-water 

 waves, as also the formation of the svstem of diverging 

 waves that precedes any body moving along through the 

 water, are all explained as due to the existence and super- 

 position of two infinite trains of waves of nearly equal wave 

 lengths and amplitudes. 



Those interested in the flow of water in rivers will find in 

 Vol. VI., No. 23, of Indian Engineering, a translation by Cun- 

 ningham of Bazin's "Discussion of Experiments on Velocity 



