308 



SCIENCE, 



[Vol. IV., No. 



the fact and the importance of that waste by 

 cylinder-condensation which is only to-day 

 becoming recognized as an essential element 

 in the theory of the ' real ' steam-engine of the 

 engineer, as ' distinguished from the 'ideal' 

 engine of the authors of the theory of thermo- 

 dynamics, and which is recognized as im- 

 peratively demanding consideration, if that 

 theory is to be made of practical use in engi- 

 neering. Watt's discovery of this ' cylinder- 

 condensation ' led him to the invention of his 

 separate condenser, and of the long-neglected 

 but now familiar steam-jacket, — an attachment 

 which was, for man} T years, only seen upon the 

 Watt or Cornish engine, and was almost never 

 used elsewhere. It has now come in with the 

 compound engine, and is familiar to every 

 engineer. Watt also found that this action 

 placed an early limit to the gain derivable by 

 expansion. 



The work of Watt in the sj'stematic experi- 

 mental study of the steam-engine was not 

 taken up by his successors in the profession 

 until about the beginning of the present half- 

 centnry, or a little later, when Hirn in France, 

 and Isherwood and the navy department in 

 this countiy, began the work which has now 

 become classic. Defective as some of this ear- 

 lier work may be by some regarded, it was of 

 inestimable value ; and Hirn, and his assistant 

 and colleague, Hallauer, will never be forgot- 

 ten as prominent among the pioneers in this 

 all-important line of research. Mr. D. K. 

 Clarke of Great Britain, one of the first of the 

 new race of engineers, interested alike in the- 

 ory and in experiment, familiar alike with 

 the science and the practice of engineering, 

 must be placed beside these investigators as 

 having persistently called attention to the loss 

 of energy revealed by them, and b}~ his own 

 investigation of the wastes occurring in the 

 steam-cylinder of the locomotive. This work 

 began, in his case, as long ago as 1855. 



Hallauer was one of the first to recognize, 

 and frankly to admit, the defects of the 'ideal' 

 treatment of the theory of the steam-engine, 

 and was as prompt in his acceptance of the 

 inevitable as was his preceptor. As Hirn says, 

 breaking away from the old sj^stem, his prog- 

 ress was rapid and satisfactory. Seizing with 

 avidity experimentally determined facts, he 

 held fast to the knowledge thus acquired, and 

 demanded that theory should precisely conform 

 to fact. His work upon the compound en- 

 gine was especially fruitful ; and his knowledge 

 of theory, and his skill in its application, ren- 

 dered his work at once available. He studied 

 also the data given him \>y Widmann, relative 



to the performance of marine engines, and de- 

 duced, from his examination of the phenomena 

 here revealed, the proper methods of increasing 

 their efficiency. Uniting, in a rare degree, the 

 practical sense with the intellectual cast of mind 

 of the scientific man, he was able to make his 

 work immediately and most effectively useful. 



Referring to his personal character, Hirn de- 

 scribes him as possessing the most admirable 

 qualities. Kindly, affectionate, modest, and 

 yet intellectually great, Hallauer united with 

 these prepossessing characteristics the most 

 irrepressible energ} r and mental force. The 

 last words in the eulogy by his friend Hirn 

 are those of personal regard and of deepest 

 affection . 



Hallauer wrote many papers, 1 the first being 

 an account of the method adopted by Hirn for 

 determining the quality of steam by means of 

 the calorimeter. The greater number were 

 descriptive of his experimental investigations. 

 He was an honorary member of the Societe* 

 industrielle de Mulhouse, and of the American 

 society of mechanical engineers, and was a 

 member of the Societe des ingenieurs civils de 

 Paris. The writer wishes to add to the eulogy 

 of Hirn, if it be possible to so add to it, this 

 tribute of kind remembrance of one who, even 

 were he not so distinguished a colleague in the 

 professional fraternities, would none the less 

 demand the most earnest expression of admi- 

 ration, esteem, and respect. 



Robert H. Thurston. 



THE SYNOPTICAL FLORA OF NORTH 

 AMERICA. 



The second portion of Professor Gray's 

 ' Synoptical flora of North America ' has ap- 

 peared, six years after the publication of the 

 first part, which contained the gamopetalous 

 orders following Compositae. The present in- 

 stalment of this important work — the most 

 important contribution (with the exception, 

 perhaps, of the Genera plantarum of Bentham 

 and Hooker) made in late years to systematic 

 botany — treats of the plants of North America 

 (exclusive of Mexico) belonging to the families 

 which precede those elaborated in the previous 

 volume, which took up the ' Flora ' where it 

 was left more than forty years ago, at the end 

 of the second volume of Torrey and Gray's 

 ' Flora.' The present publication is devoted 

 to an elaboration of the families (Caprifoliaceae 

 to Compositae) embraced in the second volume 



1 Published by Gautbier-Villars, Paris. 





