ERASMUS DARWIN LEAVITT. 843 



years, and to install it in duplicate, to avoid the loss that would 

 otherwise arise from any delays caused by accidents to the plant. 



Mr. Leavitt stood for low speed engines of high economy, and to this 

 end he used a complicated valve gear. The initial cost of such engines 

 was high, but he always justly maintained, and in this he was upheld 

 by Mr. Agassiz, that the cost of any engine was of slight account 

 compared to its efficiency. Many experts have doubted if this holds 

 true for hoisting engines, on account of the irregularity of the load. 

 It is only of recent years that it has been generally acknowledged that 

 high efficiency hoisting engines justified their expense. 



The "Superior," installed in 1883, was the largest hoisting engine 

 Mr. Leavitt built for the Calumet and Hecla. It was an inverted 

 compound beam engine with cylinders 40' and 70' in diameter. The 

 fly wheel and the belt wheel were both 36 ft. in diameter. This 

 engine was designed to hoist six four ton skips from a depth of four 

 thousand feet, and also to run four Rand compressors. As this was 

 vastly in excess of the needs of the day, the engine was looked on as a 

 foohsh monster by many people. In 1911 it was hoisting five ton 

 skips from a depth of six thousand feet, and it is still doing efficient 

 work to-day. 



The steam stamps that Mr. Leavitt designed for the Calumet and 

 Hecla marked a very distinct advance in the construction of such 

 machinery. The distinctive feature of these stamps is a steam 

 cylinder with two pistons, one with steam on top to give the blow, 

 while under the other is a constantly applied reduced pressure to lift 

 the stamp, the steam being forced back to the boiler with each blow. 



Mr. Leavitt was not inclined to talk of his achievements. Once 

 when he was asked how he got the idea of the Leavitt stamp, he 

 replied : " One day in the Calumet mine, I stepped on the man engine 

 at the twentieth level to go to the surface. I had no thought how 

 to meet the problem at the moment. But when I stepped oflF, about 

 twenty minutes later, the whole scheme was clear in my mind." To 

 properly appreciate this feat, one should realize that the man engine, 

 now obsolete, offered an absorbing and somewhat hazardous method 

 of transportation, which fully occupied the attention of most people 

 making use of it. 



One of Mr. Leavitt's pumping engines for the Calumet and Hecla 

 mills, had a capacity of sixty million gallons in twenty-four hours. 

 It remained the largest pump of its day, until superseded by an engine 

 of seventy-five million gallons per twenty-four hours, designed by 

 Mr. Leavitt for the sewer works of the City of Boston. 



His designs for Calumet included sand wheels of metal, instead of 



