236 



SCIENCE. 



[Vol. V., No. 111. 



reduction. Copper is finding new and important 

 applications in the new alloys, phosphor-bronze, 

 manganese-bronze, and other compositions. 



The working of heavy masses is demanding the 

 construction of larger hammers ; and it is becoming 

 seen that light steam-hammers are actually injurious 

 to the parts forged by them. Testing-machines are 

 now in daily use, in the hands of the engineer, to 

 determine the exact value of the metals proposed for 

 use in his designs, and to exhibit the strength of 

 completed members. 



In bridge-construction, the St. Louis bridge was a 

 novel departure in the use of steel in compression ; 

 and the New- York and Brooklyn bridge is an equally 

 successful example of application of wires for sus- 

 pension over long spans. The new bridge over the 

 Forth exhibits still another modern 

 novelty in its great cantilevers, the 

 only known expedients for success- 

 fully spanning seventeen hundred 

 feet with a rigid structure. In rail- 

 road and canal construction, the ri- 

 valry between the two systems of 

 transportation is best illustrated by 

 the enormous canals, now in progress 

 and proposed, to connect ocean with 

 ocean, and sea with sea, and, as in 

 the case of the Manchester ship-canal, 

 to take ocean-going ships into the 

 interior of the country. This led to 

 the study of harbor-construction, and 

 reference to the methods of mak- 

 ing and handling blocks of masonry 

 weighing three hundred and fifty tons 

 each, in the building of their sea- 

 walls. A new and great improvement 

 in the methods of supply of air for 

 respiration, to the workmen sent into 

 the depths during the operations just 

 referred to, is that of absorption of 

 exhaled carbonic acicl by a basic salt, 

 and the introduction of oxygen from 

 under compression in small tanks 

 carried by the diver, who is thus enabled to remain 

 under water for considerable periods of time. In 

 tunnelling in red sandstone, a speed of from ten to 

 fourteen yards per day is attained, and of twenty-four 

 yards in chalk. Dynamite and tunnelling machines 

 are making this great progress possible. 



Progress in motors has not been rapid during late 

 years. The best of recent double-cylinder non-con- 

 densing steam-engines demand but two pounds and 

 seven-tenths of coal per horse-power and per hour; 

 while the condensing-engine has worked down to 

 about a pound and a half. The gas-engine is gradu- 

 ally coming forward as a rival of the steam-engine in 

 small powers ; its greater safety, and the reduction of 

 current expenses in various directions, giving it a 

 superiority in some respects. Water-wheels have 

 attained an efficiency of eighty-five per cent; and the 

 turbine, with its high efficiency, offers great advan- 

 tages in application where the fall is low, or the 

 variation of height of tail-water considerable. In 



the transmission of power, the introduction of water, 

 steam, and compresed air, sent out from a central 

 station, is a promising direction of progress. 



COFFINS OF THE SEVENTH CENTURY. 1 



While digging a trench recently in the rue Salande 

 in Paris, an ancient burial-ground was encountered. 

 The discovery was made among the rubbish and 

 ruined walls of the old Gallo-Roman outskirts at a 

 depth of about one and one-half metres. Nineteen 

 coffins made of plaster, and four or five of stone, were 

 the most interesting things exhumed. The full ex- 

 tent of the burial-ground could not be determined, 

 because it extends beneath some houses. That all 



COFFINS OF THE SEVENTH CENTURY. 



the sepultures belonged to Christians is probable 

 from the fact that they invariably pointed toward the 

 east, and by the Christian symbols. The coffins be- 

 longed to the seventh, eighth, and ninth centuries. 

 Previous to this period they had been made of stone, 

 but those of the epoch under consideration are mostly 

 of plaster. The coffins all had the shape of an elon- 

 gated trapezoid, being narrower at the foot, and were 

 found filled with dirt, the covers having given way. 



The plaster sarcophagi are not unique, since fully 

 two thousand have already been reported as found. 

 Figures are usually imprinted upon the exterior of 

 the head and foot, but not more than one or two in 

 a hundred are ornamented on the long side. The 

 cross emblem of Christianity, inscribed in a circle 

 symbolical of eternity, is the predominant form of 

 ornamentation. There are numerous other ornamen- 

 tations, but it is difficult to classify them, or to under- 

 stand their signification. 



1 Abridged from Science et nature. 



