UTILIZATION OF SOLAR ENEEGY ACKERMANN. 



151 



In 1878 Moiichot used a boiler made of many tubes placed side by 

 side (pi. 1) and having a capacity of 100 liters (70 for water and 30 

 for steam). 



Mouchot seems to have been the only inventor of a solar plant, with 

 the exception of Shuman, who has had his apparatus tested by inde- 

 pendent engineers. The following refers to Mouchot's plant. In 

 Comptes Rendus, Vol. 94, 1882, pages 943-915, M. A. Crova reports 

 that — 



The minister of public works appointed two commissions, one at Constantine 

 and the other at Montpellier, to malie experiments with two identical mirrors 

 of 5.22 square meters in section normal to the sun's rays and to evaluate their 

 practical utility. 



The commission of IMontpellier was composed of MM. Duponchel, engineer in 

 chief of Pouts et Chaussees, as president ; Col. Fulcrand, R. E. ; Guibal, and 

 myself. 



The experiments (at Montpellier) lasted from January 1 to December 31, 1881, 

 and were made from hour to hour every day during which the sun was bright 

 and the observations possible. 



The solar rays concentrated at the focal line of the mirror were received on 

 a black boiler placed at the axis and which was inclosed by a glass shade. 



The number of major calories utilized, divided by those incident, received in 

 one hour upon 1 square meter of surface normal to the rays, gives the efficiency 

 of the apparatus. 



Here are the principal results obtained during 176 days which gave 930 ob- 

 servations, during which 2,725 liters of water were distilled. 



Moyenne g(^ii&rale dcs raleurs mesur^es pendant Vann^e 18S1 et rapportees A 



i™'?. ct d, 1^. 



Chaieur ref ue directemeut . . . 

 Chaleur utilis^e par rappareil 

 Moyenne des rendements 



Calories. 



G16. 1 

 258.8 

 .491 



Maximum 

 calories. 



945 

 547.5 

 .854 



25 Avril. 

 15 Juin. 

 14 Juin." 



The author has purposely not translated the last five lines for fear 

 of making a mistake. He is unable to interpret the results; but as 

 they represent an important and independent investigation lasting 

 a year, they are given in the hope that some of his audience may be 

 able to throw some light on the matter. 



Next came that versatile engineer and successful inventor, John 

 Ericsson, a Swede by birth and an American by adoption. He made 

 an immense number of experiments, extending over 20 years, with 

 costly apparatus, to determine the solar constant, and later on made 

 apparatus for the practical utilization of solar radiation. All these 

 experiments were made at his own expense, and he tells us they cost 

 him £20,000 ; and having done all this work, the conclusion he arrived 

 at was : 



The fact is, however, that although the heat is obtained for nothing, so ex- 

 tensive, costly, and complex is the concentration apparatus that solar steam is 



