Direct Line Favoured.

Coming now to the second proposition, passing Mount Pleasant to the west. This is unquestionably the most direct line between Christchurch and Lyttelton, as it involves a distance of only six miles of line from station to station, against 10 miles 60 chains by the shortest route to the east. Starting from Christchurch at the same point as the other line, and at an elevation of 15 feet above high water, it will rise five feet in the first mile, will fall eleven feet in the second mile, and will then be level to the foot of an incline of 1 in 50 which will lead to the mouth of a tunnel 34 feet above high water, and 29 feet above the level of Lyttelton station. It is proposed that this tunnel be carried through the mountain for the length of 2,882 yards, and having completely pierced it, the line will descend to the level of the quays at Port Lyttelton by an easy gradient of 1 in 200, and without any works being required of an extraordinary character.

In all respects (saving and excepting the tunnel), it admits of no doubt that this western route is the preferable route for a line of railway between Christchurch and Lyttelton. This line is very much shorter than any that can be carried to the east of Mount Pleasant; the works on either side of the tunnel are void of difficulty, and may indeed be described as light; there are no heavy side or other cuttings; no bad curves, as upon the eastern lines; no heavy embankments and no objectionable gradients. The stations are well situated both at Lyttelton and Christchurch, and are placed at points from which the line will admit of extension, either inland or to other shipping places, should the need of the colonists require it.

The construction, however, of a tunnel of such considerable length as that proposed on this route, renders it necessary to enter very carefully into consideration concerning the nature of the ground through which it is to be worked. I am instructed that the approaches at both ends will be through an alluvial deposit of clay with boulders. The mountain itself presents all the features of volcanic rock, exhibiting a series of lava streams dipping from 1 in 10 to 1 in 15 page 35 towards the north. The lateral breadth of these streams is not great, each stream consisting of from 10 to 30 feet of rock covered with from three to ten feet of ashes and scoria compressed into rock. These streams of lava vary in colour and hardness. Samples which have been brought to England, and which I have inspected, exhibit no indications of special difficulty except in one case; but from the position of the strata, that stone appears likely to be only occasionally met with, and although hard, it is by no means as hard as many through which I have had to tunnel. I am led to understand that it appears

Constructing the Christchurch-Lyttelton Tunnel.
Photo, courtesy Lyttelton Harbour Board.)
A view of the tunnel works, 1866, shewing Peacock's store on the left and the Union Bank on the right.

the one tunnel in the direct route, as the former present a greater number of working faces, but in a place like Canterbury, where labour is not abundant, not so much weight can be attached to this consideration as might be the case elsewhere. It is estimated that the Sumner line could be constructed in three years and the direct line in five years, an opinion confirmed by consultation with experienced contractors.