478 Intelligence and Miscellaneous Articles. 



as 1843, I published results of my experiments, showing that the 

 whole heat resulting from the condensation of steam in the cylinder 

 of an engine working expansively should be found in the condenser, 

 after allowing for known losses from other causes — a result which 

 subsequent experience has steadily confirmed. 



I allow the propriety of Dr. Rankine's disapprobation of my re- 

 mark, that M. Hirn was borne down by scientific authority in alter- 

 ing his opinions on the results of his own experiments, as, after all, 

 the publication of this change of opinion was his own free act. 

 Though I said " apparently borne down," the expression was incon- 

 siderate, and I freely retract it. I cannot forget that I am indebted 

 to the courteous kindness of Dr. Rankine for spontaneously sending 

 me valuable scientific information, which in my comparatively iso- 

 lated position here I could not otherwise have easily obtained ; and 

 though I reluctantly differ from him on some points of scientific 

 theory, my high appreciation of his intellectual superiority will 

 always cause me to respect and value his opinion, whether for cen- 

 sure or approbation. 



While thanking Mr. Croll for his remarks on my uncertainty 

 about the estimate of work done by heated air in the shape of raising 

 the. weight of the atmosphere, and on the specific heat of air, I 

 would beg to refer back to my chief difficulty on this latter point, 

 which perhaps I did not state with sufficient clearness, viz. the dis- 

 appearance of energy in the supposed experiment. What I meant to 

 express was this : — There must be more heat in the air after expan- 

 sion than before, because the energy which might have been availed 

 of by allowing the atmosphere to fall back into the vacuum, and thus 

 produce work, has disappeared, and we can imagine no other equi- 

 valent for it. And the specific heat of the expanded air, or its capa- 

 city for heat, is greater because it does not show this increase of 

 quantitative heat. 



Not having been able to make the result of experiment agree 

 with the dynamical theory as to the direct conversion of heat into 

 work, I have been long pondering on some consistent explanation of 

 the physical facts, which have continued to present themselves in 

 my researches. On this subject I had a thing to say, but let it go 

 for the present, and now I will return with renewed energy to the 

 experimental investigation of this very interesting but still perplex- 

 ing subject. 



Believe me, Sir, your most obedient Servant, 



Palermo, April 4, 1864. Joseph Gill. 



ON THE HEAT OF THE STINTS RAYS. BY M. HAGEN. 



M. Hagen made a communication to the Berlin Academy on the 

 Heat of the Sun's Rays ; he had taken some observations made in 

 Madeira by the late Dr. Hagen as a basis. 



The most important results were — 



1. That the height of the atmosphere, assuming that the layers of 

 air have the same power of absorption, is only equal to the 173rd 

 part of the earth's radius. 



2. The amount of the heating effect possessed by the sun's rays 



