152 WiHConsm Academy of Sciences^ Arts, and Letters. 



cessful attempts have been made to discover a substitute for steam 

 as a source of power, there always having been found insurmount- 

 able obstacles, inseparably connected with the use of all other 

 agents ; difficulties which science and the best mechanical skill 

 have failed to overcome. Quite a number of years will probably 

 yet elapse, ere these hindrances are pushed aside by the spirit of 

 investigation and invention which pervades the age in all civilized 

 countries. But supposing the successful employment of a more 

 suitable and economical motor might be rendered practicable, 

 during the coming week, month or year, the expense necessary to 

 secure the change would preclude its rapid adoption by many 

 using the present devices. It would in fact be so long before the 

 present arrangements could be superseded that it must still be 

 worth our time to strive for improvements in the manner of em- 

 ploying the power we now have, and to gain some knowledge in 

 which direction, farther improvement in its safe and economical 

 ■use may tend. 



Practical experience has taught us, in the past twenty-five years, 

 that there was no economy in the " old time practice " of using 

 steam at a low temperature and pressure for all purposes. The 

 direct advantages accruing from its use at high pressure, securing 

 high piston speeds, and expanding the steam to nearly zero, have 

 been very large. This change came gradually. Many improve- 

 ments were necessitated, but now the six to fifteen pound pres- 

 sures of forty-five years ago, and large unsightly engines are sup- 

 planted by pressures of fifty to two hundred pounds, and engines 

 of half the size which give the same equivalent of work. As the 

 economy of the higher temperatures becomes generally appreci- 

 ated, the greater the demand will be for them. 



The principal impediment still existing to progress in this di- 

 rection is due to the limited strength of the present forms of the 

 steam generators. The boilers of the future must be improved 

 so that safety may be insured, being either constructed in sec- 

 tions, or of material with greater strength, also not complicated 

 in design and of moderate cost. That the most important of 

 these requirements have not been realized, is only too apparent 

 from the many accidents continually occurring in different sec- 



