E. DoBSON. — State of Applied Science in Ganterhury. 143 



pose o£ di'ainage, water supply, or other engineering works, in whicli the 

 rate of fall is an important element. 



Health op Towns-. — From the drainage of the country we pass, hy a 

 natural transition, to that of the towns, and to those questions which may 

 be classed under the general head of sanitary engineering. And here it 

 must be confessed with regret that, beyond the abolition of the cesspool 

 nuisance, there is no progress whatever to record. 



Although numerous schemes of drainage have been proposed for the two 

 principal towns, viz., Lyttelton and Christchurch, nothing has yet been done 

 towards their realization. This is the more to be regretted, as the Municipal 

 Councils of both towns having approved of the system of removing the solid 

 sewage, at short intervals, by scavengers, the question is narrowed to that of 

 the disposal of the house slops, the outfalls for which would be the sea in 

 the one case, and the Rivers Avon and Heathcote in the other. 



Practically, therefore, the only question to decide is, whether they shall be 

 carried down the streets in the open side channels, or in underground pipes. 



Now, it is worth while to glance for a moment at the physical confor- 

 mation of the two towns, as they may be considered extreme types of exactly 

 opposite cases. 



Lyttelton is built in the crater of an extinct volcano, on a series of spurs 

 and gullies, the streets stretching up the steep hill-side to the height of 200 

 feet above the sea, to which there is ample fall from every part of the town. 

 But Lyttelton, unfortunately, has no water supply beyond what is derived 

 from a few deep wells near the beach, which are exhausted in the summer 

 months, making it necessary, at times, to bring water in coasting vessels for 

 the use of the town. In this case, the work to be done is to provide and 

 raise an ample supply of water to the upper part of the town, and to flush 

 the gutters from the street mains, the fall in the gutters being so great that 

 they can be effectually cleansed by this means. The water might be taken 

 from the artesian springs in the tunnel, or from the Heathcote River ; in the 

 latter case being brought from the plains, through the tunnel, in pipes. 



Christchurch on the other hand, is an example of a totally different 

 combination of circumstances. The town may be said, in general terms, to 

 lie on a plain, sloping gently to the eastward ; the western side of the town 

 being about 23 feet, and the eastern side about 9 feet, above high watermark. 



But although the fall of the ground to the eastward is ample for under- 

 ground drainage, which can be brought to a regular gradient, the irregularities 

 of the surface are so great, that the fall of the street gutters is in many places 

 barely sufiicient to allow the water to run, much less to allow them to act 

 as channels for offensive matters. 



Here, then, the proper course is to lay. underground pipes to carry off 



