594 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



GAS-ENGINES. 



The past year also witnessed the first practical introduction 

 into this country of a most ingenious improvement in gas- 

 engines, known as the Otto "Silent" gas-engine, a German 

 invention, and an improvement of the Langen-Otto gas-en- 

 o-inc, that attracted such attention in the machinery depart- 

 ment of the Centennial Exhibition from the novelty of its 

 mechanism. We have no space to enter into details of this 

 new machine further than to state that, as its name indicates, 

 it is noiseless in action ; that the consumption of gas is auto- 

 matically regulated by a governor of peculiar construction 

 in accordance with the amount of work thrown on the engine ; 

 that the speed of the engine remains at all times uniform ; 

 that it is very economical, requiring but 21^ cubic feet of 

 gas per indicated high -pressure per hour; and that it is 

 available for higher powers than has been the case with for- 



ner gas-engines. 



Where moderate and intermittent power is required, as, for 

 instance, for running hoists in stores and warehouses, printing- 

 presses, ventilating large buildings, and the like, where power 

 is wanted perhaps but a few hours during the day, and at ir- 

 regular intervals, the advantages of this class of engines over 

 the steam-engine is apparent, since the engine is always ready 

 to be started and to give out at once its full power. There 

 is no boiler requiring firing, no coal, ashes, dirt, or pumps. 



THE INCRUSTATIONS ON BRICK WALLS, 



which in damp localities, or after a heavy rain has soaked 

 them, causes such a disfigurement of brick house-fronts in 

 many cities and towns, has been made the subject of two 

 very good papers during the past year, which satisfactorily 

 brino; out all the causes that contribute to this nuisance. Mr. 

 William Trautwine shows that one cause of the trouble is to 

 be found in the very general substitution of coal for wood in 

 burning bricks (and the lime used in the mortar). As this 

 coal always contains more or less sulphur, the author ad- 

 vances the opinion that the sulphurous vapors generated in 

 the kiln by its combustion (together with air and moisture) 

 around and through the clay of intensely heated bricks for 

 several days would suffice to convert a certain variable per- 



