Maculla Hot Spring in Arabia. 35 



from the clouds, nor yet rain, as the atmosphere contains none ; 

 nor yet can we plausibly refer it to the Nile, as between this 

 spring, which is nearer the sea, and the above river, there are 

 brackish as well as other fresh-water springs, therefore, only 

 from the sea itself, and this issuing through igneous rocks, 

 which is actually the case, is purified, and that by the sub- 

 terraneous heat assisted by filtration, whilst the former pass 

 through Neptunean rocks ; occurrences which one would at 

 first be apt to consider as decisive. Indeed, it only remains to 

 shew, whether rock-salt, &c. exist in this neighbourhood (near 

 Kenek), to set the point at rest, but the presence of which, 

 being rather pushed for time, I never was so successful as to 

 ascertain, and therefore must leave it for some future traveller 

 to determine, as well as intrust to some ingenious chemist the 

 analysis of the accompanying mineral water, since my present 

 station is very far from affording me the means of conducting 

 scientific investigations. 

 Bombay, May 1837- 



On the Fallacies of the Rotatory Steam-Engine. * By John 

 Scott Russell, Esq., M.A., F.R.S. Ed., Lecturer on Na- 

 tural Philosophy. 



It has been represented to me by the Secretary, that the ob- 

 jects of this Society will be materially promoted by any disqui- 

 sition in which the fallacious views that are sometimes enter- 

 tained upon important mechanical subjects shall be clearly ana- 

 lyzed, and the errors pointed out into which the authors of 

 supposed improvements have been drawn, either by reasoning 

 accurately on false grounds, or making erroneous deductions 

 from established principles. I feel it, therefore, to be my duty 

 to make such contributions to the efforts of this most valua- 

 ble Association, as my humble abilities enable me to produce ; 

 and I have selected for this purpose the Rotatoi-y Steam-En- 

 gine, as a subject upon which erroneous views are widely pre- 

 valent, upon which much ingenuity and mechanical skill is 

 every day expended, and which belongs to the same category 



• Read before the Society of Arts for Scotland, 15th March 1837- 



c2 



