ENGINEERING. 



ENGINES, SOLAE. 



251 



holes running from top to bottom. Parkes 

 pronounced the usual practice of bonding un- 

 necessary, and also placed his blocks on the 

 edge, instead of choosing a broad form and lay- 

 ing them flat, thus exposing as little surface as 

 possible in proportion to the weight to the 

 lateral force of the waves. 



In the first excavations for the Panama 

 Canal, at Emparador, the nature of the ground 

 was found to be much more favorable than was 

 assumed in the plans. In making the engi- 

 neers' estimates it was supposed that a stratum 

 of hard rock would be found underlying the 

 soil at a depth of about 12 feet along the route 

 of the canal. In the first borings the instru- 

 ment descended to the depth of 37 feet with- 

 out striking any rock, and then, after penetrat- 

 ing a layer of rock only 6 feet thick, went 

 down to the depth of 64 feet without encount- 

 ering anything but a mixture of clay and soft 

 stone. The route of the canal from one side 

 of the isthmus to the other has been cleared of 

 trees and other obstructions to the width of 

 from 60 to 90 feet, and 125 miles of paths 

 branching out from the canal route have been 

 constructed. The climate has proved terribly 

 fatal to the skilled workmen and superintend- 

 ents brought from Europe. The work of exca- 

 vation was stopped during the rainy season and 

 resumed in October. It has been ascertained 

 that no rock excavations will be necessary be- 

 tween Colon and Lion Hill. At the latter sta- 

 tion the steam sounding apparatus showed that 

 the excavation will be in soft clay layers formed 

 by the degradation of a greenish pyroxenic 

 rock. At other places the soundings have re- 

 vealed to the depth of 80 feet a succession of 

 derived rocks growing softer and softer. The 

 mellow soil has also been found unexpectedly 

 deep along the route. 



The work of reclaiming the swamp and 

 overflowed lands surrounding and extending 

 south of Lake Okechobee, opening to cultiva- 

 tion a tract covering 17,000 square miles of the 

 area of Florida, has been undertaken by a 

 combination of Philadelphia capitalists. The 

 State has entered into a contract by which one 

 half of the 8,000,000 acres to be redeemed will 

 become the property of the company. This 

 tract embraces every class of Florida soil, much 

 of it being admirable sugar-land, and contains 

 valuable deposits of hematite ore and marl. Lake 

 Okechobee covers an area of 1,000 square miles. 

 The main feeder of the lake is the Kissimmee 

 River, which discharges 207,360,000 cubic feet 

 of water per diem. The rate of evaporation is 

 one third in excess of the inflow, so that for eight 

 months of the year a large portion of the lake- 

 bed is dry. During the four rainy months the 

 water overflows vast tracts of the surrounding 

 country. The plan of reclamation is to con- 

 struct a drainage-canal 21 miles in length and 

 44 feet wide, to the St. Lucie River. The 

 canal is to have a fall of 1 foot a mile, giving 

 a calculated velocity of 2 miles ao hour, and 

 discharging 733,708,800 cubic feet a <\ay. The 



plan is similar to the one proposed to the 

 national Government by Colonel Meigs in 

 1879. The level of the lake is 25 feet above 

 mean low tide. The artificial outlet will great- 

 ly diminish its area. In addition to this canal 

 it is proposed to dig another to the Caloosa- 

 hatchie River, which flows into the Gulf of 

 Mexico, to deepen and straighten the streams 

 which empty into the lake, and to dig lateral 

 drains, and tap the ridges separating the saw- 

 grass from the Atlantic and from the Gulf, 

 thus draining all the extensive tracts of worth- 

 less land in that section. The work on the 

 principal canal has been commenced. It is 

 done by steam-dredges, two working side by 

 side and excavating the entire cut as they pro- 

 ceed. They are constructed on the continuous- 

 ladder principle, working like the buckets in a 

 grain-elevator. The quantity of earth to be 

 removed in the main drainage-canal is esti- 

 mated at 9,000,000 cubic yards. The excava- 

 tion will cost, according to the estimate of 

 Menge, the designer of the dredges, only two 

 cents a cubic yard. 



ENGINES, SOLAE. French physicists have 

 addressed themselves with encouraging experi- 

 mental results to the utilization of the sun's 

 heat for generating the steam to work mechan- 

 ical motors. If only a minute fraction of the 

 radiant energy of the sun intercepted by the 

 earth could be directly utilized, it would fur- 

 nish a superabundant supply of mechanical 

 power for all of man's requirements. When 

 the coal-beds, which represent stored-up en- 

 ergy derived from the sun and preserved from 

 a former geological period, have been ex- 

 hausted, there remains, so far as science is able 

 to predict, no other abundant chemical source 

 of energy. The current supply of solar heat 

 must then be depended upon. The terrestrial 

 forces of wind and water power, into which a 

 portion of the intercepted radiant energy is 

 converted, will probably remain to the end of 

 time the natural agencies upon which the 

 world must rely for the chief part of its me- 

 chanical work. In those parts of the earth's 

 surface upon which the direct rays of the sun 

 beat without remission through the whole 

 year, their heating effect can be converted into 

 mechanical power by means of mechanism of 

 sufficiently neat construction and delicate ad- 

 justment. The heat of the sun on the earth 

 is estimated to be equivalent to the melting of 

 a crust of ice 103 feet thick, covering the 

 whole surface of the globe, each year. The 

 greater part of this heat is absorbed by the 

 atmosphere. The average heating effect of the 

 sun's rays, at the level of the ground within the 

 tropics, is estimated to be enough to melt a 

 layer of ice 85 feet in thickness. If the heat 

 falling upon one acre could be entirely utilized 

 in producing motive power, it would give 4,000 

 horse- power for nine hours a day throughout 

 the year. 



Mouchot has experimented many years upon 

 the utilization of the sun's heat as a source of 



