VIII. THOMAS KENNEDY. 



In railway location where curves not sharper than 10 

 chains radius are to be used no great advantage is gained 

 by making contour maps of the route, as the usual practice 

 in New South Wales of writing the reduced levels on the 

 plan gives quite as accurate results whilst the office work 

 is considerably reduced. 



In rough country better results are obtained by the use 

 of contours as it is then necessary to use sharp curves. If 

 curves of five chains radius are to be used, then to get the 

 best results from cross sections they should be taken almost 

 at every chain and the heights written ou the plan. These 

 figures do not convey to the eye any impression of the 

 nature of the country, whilst by the use of contours a good 

 idea may be taken in at a glance. 



In surveying preliminary lines for a proposed railway, 

 long lengths have frequently to be staked on the ruling 

 grade; then the tacheometer system is a great assistance 

 in locating the line. The main traverse should, however, 

 be always levelled and chained as a complete check on the 

 work. This can be carried out by an assistant whilst the 

 plans and sections are being plotted. On some portion of 

 tlie Dorrigo survey alternate lines had to be staked. They 

 were run out by the tacheometrical method and checked 

 on to the main traverse at about half-mile intervals. 

 These lines served to extend the contours and a wide belt 

 of country differing in level by 500 feet was in some instances 

 shown. The advantage of having extended contours was 

 of great assistance in the location on the plan of the proposed 

 railway to the Dorrigo for over the whole ascent of 1,700 

 feet — three separate schemes have been formulated giving 

 ruling grades on each route of 1 in 30, 1 in 40, and 1 in 60 

 respectively. On the 1 in 30 and 1 in 60 it is proposed to 

 use five chain curves, whilst on the 1 in 40, the 10 chain 

 curve is adhered to, as on the latter the ordinary engines 



