624 transactions of the american institute. 



Shooting Stars. 



M. Poey, in a paper to the French Academy, states that from observa- 

 tions made at Havana, the number of shooting stars in the Northern Hemi- 

 sphere is double those in the southern. The maximum number of meteors 

 are seen in the northern between 1 and 2 o'clock, in the southern between 

 2 and 3. 



Artificial Rainbow. 



The Cosmos speaks highly of J. Duboscq's contrivance for imitating a 

 rainbow in a French theater. He employs an electric light made by 100 

 Bunsen elements. Its rays are transmitted in a parallel direction by means 

 of a lens, through a slot in the form of an arc to a double convex lens of 

 very short focus, from which the rays pass to a prism and emerge with 

 sufficient divergence to make an effective rainbow, during the ordinary 

 illucaination of the stage, on a screen 18 or 20 feet distant. 



Unequal Power of the Organs of Hearing. 



In making experiments with tuning forks, by holding one to each ear at 

 the same time, Herr Fessel, of Cologne, has discovered that ears do not 

 possess an equal power of hearing. It appears that from numerous trials 

 on various individuals, they hear best with the right ear, but in no case 

 has the hearing been found exactly alike on the two sides of the head. 

 The difference in the sight of the right and left eye is also more common 

 than is generally supposed, because the impression made by the weaker 

 eye is absorbed or dissipated by that of the stronger eye, which has gene- 

 rally been made stronger by previous use, the practice being common to 

 favor one eye. 



This item gave rise to an interesting and spirited discussion, in which 

 Messrs. Nash, Gavit, Parmelee, Rowell, Roosevelt, Bartlett and Garvey 

 participated. 



Steam Pressure Gauges. 



Dr. Warren Rowell, from the committee to examine a new Mercury 

 Steam Pressure Gauge, submitted the following report : 



The committee to whom was referred the Mercury Pressure Steam 

 Gauge of Messrs. Shaw & Justice, respectfully report : 



That a correct instrument to indicate the precise pressure of the steam 

 within the boiler of a steam engine, is of the first necessity. Ever since 

 the use of steam, above the atmospheric pressure, various devices to shew 

 the exact pressure have been invented. A brief sketch of the most impor- 

 tant is herewith presented. The first one was Papin's safety-valve, which 

 was simply a heavy plug of metal fitting an orifice in the cover of the 

 kettle now known throughout the world as Papin's digester. This metal 

 plug was lifted by the pressure of the steam, when above the temperature 

 desired, and of course when the pressure went down the temperature went 

 down also. This invention, (says an old author) without which steam 

 would long ere this have been abandoned, as a dangerous and ungovernar 

 ble agent, entitles Papin to universal admiration, since it has contributed 

 more than any single addition or improvement to the maturity of the steam 

 engine. The next advance was by Henry Brighton, of Newcastle upon 



