L. MECHANICS AND ENGINEERING. 405 



to greater depths, and requires no annual outlay for repairs. 

 Vienna Circular. 



ATTACKS OX OCEAN CABLES BY MARINE ANIMALS. 



In connection with the question of the possible injury to 

 ocean cables by the action of submarine animals, to which we 

 have already called attention in our pages, it is stated that 

 when the French Atlantic cable, laid in 1869, was lately raised 

 at one point for repairs about 112 miles west of Brest, it was 

 found perforated by small boring mollusks, apparently of the 

 genus Xylophaga. The outer covering of the cable consisted 

 of tarred Manilla hemp, and was bored occasionally by round 

 holes, in which their shells were found. In some places they 

 had passed through the outer covering, and between the iron 

 wires to the gutta-percha core, and in some instances they 

 had actually made numerous shallow indentations, and laid 

 bare the wire. Wherever examined, the cable was found 

 covered by adhering masses of bryozoa, etc., which, however, 

 appeared to produce no injury. 12 A, November 6, 1873, 15. 



SELF-REGISTERING APPARATUS FOR OMNIBUSES, ETC. 



A very ingenious apparatus was presented at the late ex- 

 hibition of the Institution of Civil Engineers for recording 

 passengers in omnibuses and street cars. This counts up 

 once every minute the number of passengers, and prints this 

 number and the exact time in plain figures. Each seat is 

 separate, and the weight of the passenger on the seat brings 

 the wire from the seat in communication with the recorder. 

 The instrument also records the speed of the omnibus at every 

 moment of the journey, and shows the exact time of arrival 

 and departure from each station. 12 A, IX., 54. 



PROCESS FOR DIMINISHING THE DIAMETER OF IRON OR STEEL 



CAR-WHEEL TIRES. 



It sometimes happens that, by centring, etc., the interior 

 diameter of a tire becomes so much too large that it will not 

 tit the wheel. Such defects have been corrected, for a long 

 time, by J. Fiedler, a German machinist, by heating the tire 

 red-hot, and in that condition holding it half-immersed in 

 cold water until cold ; then heating again red-hot, and im- 

 mersing the other half in the same way. In the first operation 



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