The age-herald., 1900-03-25
A Lncnmntiye,a Speed

A rGlotograrJh of a train in rap!d motion
 was recently taken by MT. Joseph Gray
 Mitchell of this dity in New York state 20
 determine the rate of speed for evidence in
 a lawsuit. The picture was made with the
 most approved apparatus and sensitive
 plates, and the result was wonderfully
 graphic Illustration, and the speed deter
 imitation computed to scientific
 Eicety. AS this was probably the first
 time photography was ever used to record
 locomotive speed, the details may be of
 Interest to photographers and others, MT.
 Kitehell's claim for originality, however,
 being only in the method of computation
 discovered.
 The print from the negative was perfect
 ly sharp save in one particular. Although
 the train was moving at the rate of 67 1-2
 miles an hour, the blurred exception ex-
 hlbatirlg motion was made use of on which
 to base the speed calculations The photo
 graphic particulars MT. Kaocheil described
 follows
 Liens, Goerz by 1O F. IT; shutter, B.
 & L., diaphragm Wide open, set at 1-10O of a second; plate, Seed 23 Sen; camera placed 200 feet from focused point diagonal plane of plate to plane of track, 120 degrees.
 'It being approximately estimated that the train would be moving at a rate ex- ceeding a mile a minute, the shutter was set accordingly to catch it at practically a standstil Thus the exposure would have to be made in 1-SS of a second or less as a body moving a mile in a minute passes through SS feet of space in a second; thus the shutter was tested to an instantaneous exposure of only 1-1O0 of second. The chief factor of interest and of value lay in the detail that the entire image of the
 locomotive was perfectly sharp as though
 it were at rest, except the spokes of the
 driving wheels descending half circle su-
 perior to the horizontal line drawn across
 hA ar n
 being more blurred in ratio to their prox-
 unity to the center vertical line at the
 point of the most superior periphery of the
 wheel. The reason for this was in the fact
 that these upper spokes travel through space at a higher forward rate of speed
 than the lower ones
 This would appear to be erroneous until
 it is understood that all parts of the en-
 zine are covering The same distance on the track in given time, yet the upper parts
 of the wheel have the general unit of forward motion plus the individual for ward motion of revolution, and the same general Forward motion, but retarded in their forward progress by backward thrust that begins at the middle forward horizontal point and ends at -the middle Horizontal posterior point. IA simple Illus t-a ton of this may Joe obtained in a spec tacle Of two brakemen running along the top elf a freight train in contrary direc- trons the one advancing in the direction of train progress moves through space at a higher rate of speed than tlne one reced- ing from the direction of train progress ''Now, by carefully measuring the extent of motion evidenced by the sphere of blur made by the upper spolses in the HOO part of second and comparing with the sta tionary impress of the lower spokes a ratio of difference in the given time is t.ohshed and one that may be used as a hypothesis, which, computed with the known diameter and other measurements of the driving wheels, will indicate the sLyeed per second, minute, or hour.