ENGINEERING. 



lable for public purposes a portion of the 

 heretofore unsightly and objectionable. 



Submarine Foundations. A new process 

 of construction is described by P. Nenkirch, of 

 Bremen, in a paper published in the " Transac- 

 tions of the American Society of Civil Engineers." 

 It has been tested practically near Bremen, with 

 the alleged result of producing monolithic subma- 

 rine foundations. The conversion of sand and 

 gravel in situ is effected by forcing commercial 

 cement in the form of powder through a pipe to 

 the desired depth. Air pressure is used, and ce- 

 ment is driven through several small holes with 

 considerable force, causing a bubbling action in 

 the wet sand, so that an intimate admixture is 

 effected. Observation shows that a natural bed 

 of sand, after having one fifth of its volume of 

 cement injected into it, occupies less space than 

 before. The space to be concreted is divided into 

 small sections 8 to 12 inches square, and each of 

 these is successively impregnated with cement, so 

 as to secure uniformity. To suspend the operat- 

 ing tube a movable tripod is erected, and the air 

 blast is carried through a flexible tube. The 

 hardening process is slow but sure, and is com- 

 paratively inexpensive. It is also applicable to 

 imbedding piles in cement, to inclosing sewers 

 already in place, and to numerous other engi- 

 neering operations of the greatest practical util- 

 ity on land and sea. 



Dynamite Dredging. Off Brunswick, Ga., 

 some interesting and successful experiments are 

 reported. The harbor of this port is formed by 

 St. Simon's Sound, opening into the Atlantic 

 through a channel having a natural depth of 

 about 17 feet at mean low water. This was closed 

 by a wreck in 1890, and although the ebb and 

 flow of the tides opened new channels, the prac- 

 ticable depth was reduced to about 11-J feet. 

 Failing in an effort to secure a share of the river 

 and harbor appropriation, Brunswick wisely de- 

 termined to act for herself, and, failing again to 

 procure a dredger, C. P. Goodyear, a lawyer, sug- 

 gested experiments with dynamite. Work was 

 begun July 8, 1891, and on Aug. 22 following 

 a depth of 13'3 feet at mean low water was 

 reported in a straight new channel. On the 

 strength of this result authority was obtained 

 from Congress to continue the work. At latest 

 accounts about 60,000 pounds of dynamite had 

 been exploded, at an expenditure of about $30,- 

 000, and a uniform gain of 4 feet in depth is re- 

 ported. Mr. Goodyear began with small charges 

 of 15 pounds, but, learning from experience, in- 

 creased them to 50, 100, and 200 pounds. No 

 tendency to shoal has developed, and apparently 

 the undertaking affords another example of suc- 

 cessful engineering on the part of a layman. 



Electricity is and must continue to be the 

 absorbing subject of investigation for engineers 

 of the younger school. No engineer, indeed, of 

 whatever school, can afford to ignore its demands. 

 Not only are such gigantic enterprises as the 

 conversion of Niagara into light, heat, and pow- 

 er commanding the attention of the world, but 

 everywhere the perennial forces of nature are 

 harnessed for the service of man. The time is 

 fast approaching when every considerable water- 

 fall will have its value, and sooner or later the 

 tremendous forces of ocean waves and tides will 

 contribute to the same end. Thus is one great 



obstacle to the use of electricity overcome 

 namely, the heavy expense of running electrical 

 plants by artificial means, involving the con- 

 sumption of costly fuel. Only a year or two ago 

 the transmission of power from available water- 

 falls and rapids was limited to short distances, 

 but now one can not read the news items of a 

 daily paper without learning of fresh instances 

 where enterprising towns draw light, heat, and 

 power from streams 5 or 10 miles distant, whose 

 only mission has heretofore been to furnish rec- 

 reation for a few fishermen. It is often the case 

 that where coal is dear, water power is cheap 

 and near at hand, rendering it possible to light 

 streets and houses better, and run machinery and 

 cars at a comparatively inexpensive rate. In 

 many States the legislatures have been so over- 

 whelmed with petitions for charters for electric 

 railways that they have been obliged to postpone 

 action in individual cases until general laws 

 could be framed in the interest of all concerned. 



That the unsightly, inconvenient, and danger- 

 ous overhead trolley systems are destined to give 

 way to conduit lines, and these eventually per- 

 haps to storage batteries, must be evident to any 

 one who watches the progress of electrical sci- 

 ences ; but whatever the ultimate outcome of in- 

 vention, natural sources of power, whether of air 

 or water, must retain a definite value. 



Electric Propulsion. The electric tramway, 

 as used mainly for passenger traffic on short 

 lines, is acquiring such importance that some 

 brief account of its principles is desirable. At 

 present, power, whether exerted by wind, water, 



FIG. 1. CONVERSION OF POWER INTO ELECTRICITY. 



or steam, is essential to the production of elec- 

 tricity, which must in turn be converted back 

 into power before it can do its work. The great 

 advantage of this lies in the marvelous facility 

 with which electricity can be sent along a wire, 

 just as water can be carried along a flume. The 

 conversion of original power into electricity is 

 effected by means of a dynamo, which consists of 

 a number of spools of soft iron wound with in- 

 sulated copper wire. A, Fig. 1, shows such a 

 spool in a simple form. Now suppose several 

 such spools mounted upon a wheel so placed in 

 relation to a powerful magnet that one end of 

 the soft wire-wound iron will nearly touch the 

 two poles of the magnet when the wheel re- 

 volves. Such is the mysterious and lightning] ike 

 action of electricity that its nature changes when- 

 ever it passes a pole of the magnet, and an elec- 

 tric current flashes not only through it, but 

 through its surrounding wire, and may be trans- 

 mitted thence to a fixed wire or rod leading any- 

 where, provided it comes back to its starting- 

 point. From any part of the fixed wire elec- 

 tricity may be drawn merely by touching it with 



