The Viagraph. 43 



the pulley X by the amount of the drop, the rubber band O 

 stre'ching to allow the necessary movement of the cord. 

 When the road-wheel and lever rise again the cord slips back 

 on the pulley, the rubber taking up the slack while the pullty 

 is held fast by a brake, consisting of a quite similar rubber- 

 tightened cord attached to a rigid part of the frame instead of 

 the lever T, and passing round a separate groove on X. The 

 pulley X therefore rotates intermittently, in one direction only, 

 to an amount proportionate to the sum of all the unevennesses 

 passed over, which amount is indicated in inches on the decimal 

 counter, and constitutes the index of unevenness. 



In order to compare the index of one road with another, it is 

 obviously necessary that the same length of each be taken as a 

 unit. For this purpose a length of 88 yards, being one- 

 twer.tieth of a mile, is convenient, and this is measured in 

 inches of paper, run off the roll C, proportionate to the scale 

 arranged. That is to say, when 88 yards of road have been 

 traversed 33in. of paper will have run off the roll. Each 33in. 

 length is measured off by the pulley at M in contact with the 

 stock roll of paper, and at the end of the length it rings the bell 

 above it, thus indicating that the unit length of road has been 

 traversed. 



In a newer form of the instrument this alarm-bell has been 

 transferred to the interior of the drum A, thus making it more 

 simple and compact, and the working parts are protected from 

 passing showers by a suitable glass case. 



A number of diagrams are on the table, showing profiles of 

 roads in Antrim, Down, Norfolk, Suffolk, Surrey, and 

 Lancashire taken by myself, also of roads near Exeter, for 

 which I am indebted to Mr. Donald Cameron, City Surveyor of 

 that town. Three examples of these profiles are given. Fig. 

 2. The f^rst is a flint road, once a main coaching route 

 from London to Portsmouth, and still carrying considerable 

 heavy traffic. It was selected by the advice of Mr. Shipton, 

 Secretary Cyclists' Touring Club, as an example of a good bit 

 of a good English country road. The second is chosen for 



