382 PIONEERS OF SCIENCE IN AMERICA. 



inch gun thirty feet long, the muzzle of which projects through 

 an opening in the stem near the bottom, and which is intended 

 to carry a fifteen-hundred-pound projectile charged with three 

 hundred pounds of guncotton. The vessel is intended to 

 attack "bow on," and to discharge its projectile from within 

 three hundred feet of the object of assault. The bill for the 

 purchase of this vessel by the United States, although it 

 passed the Senate in 1885, failed to become a law. 



" Three distinct purposes," says Mr. Church, " are apparent 

 in Ericsson's labours : first, to improve the steam engine and 

 extend the scope of its application ; next to discover some 

 more economical and efficient method for changing the mode 

 of motion we call heat into the mode of motion we call power; 

 third, to force the great maritime nations to declare the ocean 

 neutral ground, by making naval warfare too destructive a 

 pastime to be indulged in." We have seen how he worked 

 out the first of these ideas in his numerous adaptations of the 

 steam engine, and the third in the monitors and the Destroyer. 

 In trying to make the second idea practical he devised the 

 caloric engine and devoted many of the later years of his life 

 to the investigation of the solar heat and of methods of con- 

 verting it into a direct source of mechanical power. He devised 

 and constructed a solar engine in 1883, which was described 

 and illustrated in Nature (Vol. XXIX, p. 217), and laboured 

 until within two years of his death to improve and perfect it 

 In his description of this engine he showed that with reflecting 

 plates of one hundred and thirty by one hundred and eighty 

 inches and a steam cylinder of six by eight inches he could 

 obtain a speed of one hundred and twenty turns per minute, 

 with an absolute pressure on the working piston of thirty-five 

 pounds per square inch. 



He devoted himself regularly and, except for the daily walk 

 and gymnastics for his health, unremittingly to his work. Fit- 

 ting up his office and workshop in Beach Street, N^w York, he 

 occupied his whole time in investigation, experiment, and con- 

 struction, refusing to be interrupted, and shutting himself out 

 from general visitors. The callers who, in spite of his well-known 

 habits, came to congratulate him on his eightieth birthday 

 were not received. He was a man of great physical strength, 

 and some remarkable stories are told of his feats in lifting. 

 In one of them, when in youth he raised a weight of six 



