E. DoBSOisr. — State of Ajyplied Science in Canterhury. 139 



Coast routes, a set of flying levels across tlie country was taken by aneroid 

 observations, a single instrument only being used and the weatber being 

 exceedingly unfavourable ; yet tbe results compared very satisfactorily 

 botb with tbe altitudes afterwards obtained witli great care by Dr. Haast, 

 and with tbe actual beigbfcs as determined by tbe spirit level after tbe open- 

 ing of tbe Otira Eoad. In laying out tbe line across Arthur's Pass, wbere 

 tbe road descends 750 feet in a very sbort distance measured in a straight 

 line, the gradients were determined entirely by tbe aneroid, the observer 

 creeping through the dense scrub on bis bands and knees, and fixing the 

 position of tbe line, at every few chains, by the reading of the aneroid ; the 

 line thus laid out requiring but little subsequent alteration, when the 

 clearing of the timber had given an opjDortunity for the correction of any 

 irregularity in the gradients. 



Eailwats. — Passing from ordinary roads to railways, v^e have to record 

 the completion of a first instalment of the Southern Railway, constructed 

 under the superintendence of Mr. W. T. Doyne, M.I.C.E., which was opened 

 for traffic as far as EoUeston, about fifteen miles from Christcburch, on the 

 15tb October, 1866. On the Lyttelton and Christcburch Railway, which has 

 been open for traffic between Christcburch and the Heathcote Wharf since 

 December, 1863, tbe works of the Moorhouse tunnel have made steady pro- 

 gress, only about 240 yards remaining to be driven at the present time, out 

 of a total length of 2,838 yards. 



Independently of tbe interest attached to these tunnel works in a 

 geological point of view, as affording a complete section through tbe side of 

 an extinct volcano, they are of importance as an example of engineering 

 difficidties successfully overcome. 



Tbe syphon employed for the drainage of the upper half of the tunnel 

 is probably the longest of which there is any record in the history of tunnel 

 works, being upwards of half a mile in length ; whilst the system of ventila- 

 tion employed, viz., that of conducting tbe smoke and foul air through a flue, 

 formed by a horizontal brattice, into an upcast shaft near the tunnel mouth, 

 has proved perfectly effective. It is worth remarking, that the engineers of 

 the Mont Cenis tunnel have at last found it necessaiy to employ a similar 

 means of ventilation, the supply of compressed air forced into the face of 

 tbe work being insufficient to drive out the smoke which filled the tunnel 

 like a series of walls of dense fog. 



It may be laid down as a leading axiom with regard to the ventilation 

 of drives mined with gunpowder, that although fresh air may be driven in 

 by machinery, so as to produce a healthy atmosphere for the miners, tbe 

 smoke from the shots cannot be driven out, but must be drawn out by 

 creating a vacuum in the direction in which the smoke is to be drawn ; the 



