576 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



about as frst as it commences to exude from the tip of the burner. 

 There would be no difficulty in arranging the apparatus to instan- 

 taneously illuminate the whole series in each tier, but would 

 involve an escape of gas under the present arrangement. 



The burners themselves have an indestructible lava tip, which 

 acts as an insulator, and the coil of platinum wire, which by red- 

 ness inflames the gas, is set a little on one side of the gas orifice, 

 so as not to impair the jet. 



The magnifficent dome and the vast proportions of the upper 

 part of the rotunda showed to a better effect thau ever before, as 

 the windows below the spring of the dome are insufficient to irra- 

 diate the interior from the eye of the dome downwardly, and Bru- 

 midi's allegorical picture on the ceiling shows like a transparency, 

 or like a circle of celestial scenery, viewed through an opening in 

 the roof of an immense vault. 



The apparatus is ingenious and eminently effective, and it 

 deserves more than a mere passing notice, as well from its novelty 

 as from the locality of its exhibition, and the fact that from here, 

 as a centre, the invention will ramify until it embraces the area of 

 modern civilization. Last eveniuo; the dome was a^ain illuminated. 



After discussion on Dr. Vander Weyde's important paper, the 

 Association adjourned. 



American Institute Polytechnic Association 



November 22, 1866. 



1 



Prof. S. D. Tillman, in the chair ; T. D. Stetson, Esq., Sec'y. 

 Dr. J. Hirsh read a paper in reply to some remarks on petroleum 

 by Dr. Vanderweyde, relating to the oxidizing of petroleum. 



Steam' Indicator. 



Mr. F. W. Bacon exhibited a steam indicator, much smaller than 

 McMold's indicator, and said to be more sensitive and accurate. 

 The springs formerly employed, being of large size, recoiled when 

 used, in consequence of the momentum acquired, further than cor- 

 responds to the steam pressure, thus giving inaccurate results. 

 With engines of great velocity, an indicator with large springs 

 becomes entirely useless, while the instrument employed by him 

 always gave very accurate results: 



The chairman said that for years the steam indicator was known 

 as "Watts' indicator;" but the fact has been well authenticated 



