Science Gossip . Company, Ohio, as employed in making 7,500rail joints in the Buffalo street railway system. Thetrolley wire current is transformed by a rotary con-verter carried on the car into single-phase current of300 volts pressure, and then down to 5 or 7 volts byanother special transformer. The pressure being sogreatly reduced the current obtained is enormous,as much as 25,000 amperes being produced. Thejoint is made by means of fish-plates, welded on toeither side of the web under heavy pressure. Eachjoint takes fifteen minutes to complete. New Reading Microscope. — Following uponthe d
Science Gossip . Company, Ohio, as employed in making 7,500rail joints in the Buffalo street railway system. Thetrolley wire current is transformed by a rotary con-verter carried on the car into single-phase current of300 volts pressure, and then down to 5 or 7 volts byanother special transformer. The pressure being sogreatly reduced the current obtained is enormous,as much as 25,000 amperes being produced. Thejoint is made by means of fish-plates, welded on toeither side of the web under heavy pressure. Eachjoint takes fifteen minutes to complete. New Reading Microscope. — Following uponthe description in last months Physics column of thevernier microscope, made by Messrs. John J. Griffin &Sons, Limited, we here illustrate two additional instru-ments made by this same firm for somewhat similarpurposes: themeasurementof small distances. Thefirst of these is a reading microscope, the design beingan improvement upon that described in the courseof instruction in Practical Physics at the Royal. The instrument is provided with an extra fitting asshown enlarged in the top left corner of the illustra-tion, so that the microscope may be used for either,horizontal or vertical measurements. The instrumenthas an English objective and a No. 1 eyepiece fittedto the microscope tube, and is proving very useful innumerous physical measurements, such as thermp-meter calibration, indices of refraction, &c. The in-strument is made entirely of brass, so that it may beused in connection with magnetic measurements;otherwise, if iron was present in any of its parts, itwould interfere with the readings owing to magneticinduction. A Point-cathetometer.—The second instru-ment is what is known as a point-cathetometer, andis also intended for the rapid measurements of verticaldistances, but greater ones than the above referred-toinstrument is adapted to measure. Into a firm irontripod base, which is provided with levelling screws, avertical brass tube about 1 m. long and of 2 to3 cms.
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License: Licensed
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Keywords: ., bookcentury1900, bookdecade1900, bookpublisherlondon, bookyear190
