DYNAGRAPH. 



295 



make of the rails over which the car is passing, 

 and, standing beside the instrument he reads the 

 story told by the different lines as readily as if 

 they formed words and sentences. One inch 

 of the paper may represent 50 feet, or 100 feet, 

 or 200 feet of track, according to the necessi- 

 ties of the case. The 50-foot gauge is always 

 used for track-inspection, and in that case 8 '8 

 feet of paper represent one mile of track. 



The first dynagraph was made in 1874, and 

 was used on the Valley Railroad of Ohio from 

 1875 till 1878, when the present machine was 



ing the paper drums to revolve so that B re- 

 ceives the paper as fast as A delivers it. A 

 tension-regulating apparatus causes the paper 

 to pass smoothly and evenly across the space 

 marked I), which is, in fact, the recording-table. 

 Above this table is a series of pens, some de- 

 livering red ink, some black, and some blue. 

 These in turn are connected with an elaborate 

 system of mechanism leading to the rails over 

 which the car passes. Small steel rollers bear 

 upon the sides of the rails and upon their 

 upper surfaces, and act so uniformly that the 

 slightest deviation from the normal ad- 

 justment is recorded upon the moving 

 sheet of paper in the car. A separate 

 device is required to take the dynamo- 

 metrical curve of the moving train. A 

 draw-bar is mounted over the paper and 

 connects by ingenious mechanical appli- 

 ances with a fluid-chamber attached to 

 the framework of the car. Any press- 

 ure against the draw-bar is communi- 

 cated to the pen that traces the dynamo- 

 metrical curve. It is impossible intelli- 

 gibly to describe, even with the aid of 

 diagrams, all the intricate yet simple 

 mechanism that secures the results shown 

 in Fig. 2, which represents a cross-sec- 

 tion of paper after it has passed under 

 the recording-pens. A list of the work 

 done as the -car passes along at the rate 

 of twenty miles an hour will give a bet- 

 ter idea of its practical utility than any 

 attempt at detailed description: 1. 

 Alignment of rails (approximate) ; 2, 

 gauge of track ; 3, degree of curvature 

 and general alignment of the line; 4, 

 deflections and irregularities of all kinds 

 in the rails ; 5, elevation of the outer rail 

 incurves; 6, gradients; 7, oscillation of 

 car-body ; 8, exact distance run ; 9, time- 

 marks in seconds; 10, dynamometrical 

 curves (the ordinates of the curves and 

 the foot-pounds of work can be calcu- 

 lated from these data). In addition to 

 these records there is an attachment that 

 automatically discharges a small quan- 

 tity of paint against the side of the rail 

 wherever a fault occurs of sufficient im- 

 portance to require attention. This en- 

 ables the trackmen to see at a glance 

 where their services are needed, so that 

 they do not have to stop and examine 

 every joint separately. An operation in- 

 volving the wearisome task of stooping 

 to inspect the rails on both sides wherever the built. With the first instrument, which carried 

 joints show signs of wear. paper only 11 inches wide, many experiments 



When the dynagraph is in operation the pa- were tried ; and the value of the idea was fully 

 per, instead of being delivered directly upon the demonstrated. A long series of observations 

 second drum, is carried over a long table fixed was necessary, however, before the instrument 

 in the center of the car (see dotted lines E E, approximated its present remarkable accuracy. 

 Fig. 1), so that the observer can have plenty of The data furnished by the dynagraph have ena- 

 time to watch the record and make memoranda bled the management of the roads using it to 



Kiaxt hiit. IPO 



tPoYTtfc JN 

 LA-noJi.utr 



390- 



FIG. 'a. 



for future reference as the work progresses. 

 Practice has cultivated the inventor's skill to 

 such a degree that he can often tell the special 



effect material saving in running expenses, and 

 in wear and tear; for nothing consumes more 

 mechanical energy than an uneven track. 



