New Engine for Riding. , 91 



only difference between these lines and the preceding (Fig. 5) 

 being one of pressure upon the ruling edge. Such rulings are of 

 course much too fine for grating work. 



In conclusion the writer may be permitted to say that the con- 

 struction of a Ruling Machine is not the straightforward piece of 

 work which this brief account may appear to indicate. Difficulties 

 were met with from time to time which frequently necessitated a 

 modification of preconceived ideas and intentions. The work 

 throughout afforded but little opportunity for economy with respect 

 to either time or labour. Practically every portion of the machine 

 required one's best effort to be bestowed upon it; as each part was 

 either in itself of sufficient importance to call for this or was- 

 directly related to other important parts. 



It remains to express my great obligation to several gentlemen 

 who afforded unstinted help whenever appealed to. During the 

 early stages of the work, I was especially indebted to Mr. W. Stone, 

 Chief Electrical Engineer of the Victorian Railways, who generously 

 undertook the labour of cutting both the screws and grinding nuts, 

 which required a more accurate and powerful lathe than any at my 

 service, and who, throiighout subsequept operations, was ever ready 

 witli lielp, suggestions and fi-iendly criticism. 



I am likewise under even greater obligation to Professor T. R. 

 Lyle, F.R.S., who, from the initiation of the project for building 

 a machine, interested himself and others in a variety of ways with 

 a view to such assistance and encouragement as he considered would 

 best help forward the undertaking. Later he induced the Univer- 

 sity Council to permit him to make provision in 1914 for housing 

 the machine in his laboratory at the University, and for carrying- 

 on the work of its completion and improvement under favourable 

 conditions. Since his retirement from the Chair of Physics in 

 1915, he has been immediately and actively associated with all the 

 later improvements, many of which are due to him. This applies 

 especially to the calibration and adjustment of the Ratchet wheels, 

 and the elimination and correction of errors of the screw and its 

 thrust plate. These operations were prolonged and tedious, but were 

 greatly simplified by his mathematical insight and experience which, 

 to me, were an inestimable advantage and materially reduced the 

 mechanical work involved. 



My best thanks are also due to Professor E. W. Skeats, who, 

 during my association with his Department, unreservedly placed at 

 my service all the facilities his workshop and laboratory afforded. 



