1871-] Military, Civil, and Mechanical Engineering. 293 



Tunnel was so far completed that the miners from the French and Italian 

 sides of the mountain met in their respective underground passages. The 

 advanced heading has been now effectually completed, and it remains but to 

 complete it to the full necessary section in order to prepare it for the laying 

 of the railway. A provision in the original contract established the obligation 

 of the contractor to complete the contract by September next ; but now, 

 should the premium demanded by the contractor be granted, Signor Galery 

 will undertake to complete the work by March, which would permit the 

 tunnel line to be opened to Modena by the end of April. The tunnel is 12,200 

 metres, or about 7 miles 1020 yards in length. Boring operations were 

 systematically commenced at both ends on 25th January, 1863, and the work 

 will thus have occupied about seven years and two months. The cost of the 

 tunnel was originally estimated at ^2,600,000, but it is now believed that 

 the outlay will not exceed ^2,400,000. 



Ship Canals. — The Portage Lake and Lake Superior Ship Canal has been 

 cut through, and it is announced that it will be ready for the passage of the 

 largest steamers on the northern lakes in the course of the present spring. 

 This canal passes along the base of the promontory of Keweenaw, which is 

 situated on the southern shore of Lake Superior, about midway between the 

 eastern and western extremities, and extends in a north-easterly direction 

 nearly one-third of the way across the lake. At the lower part of the pro- 

 montory is a bayon called Portage Lake, which extends from Keweenaw Bay 

 on the east nearly across to the west side. To complete the navigation, a 

 canal two or three miles long had to be cut through a sand-ridge, and this part 

 of the work has been accomplished at a heavy expense. It is probable, how- 

 ever, that the navigation of Portage Lake will have to be improved, and 

 the channel deepened, before the largest lake steamers can pass through. The 

 new route, it is stated, will shorten by 100 miles the length of the voyage 

 between the Sault Ste. Marie Canal and the towns on the western coast of 

 Lake Superior. 



Railways. — The principal improvements of the present day with regard to 

 permanent way, consist in the introduction of iron sleepers in the place of 

 wooden ones. One great objection to cast-iron sleepers has always been their 

 uncertainty to preserve the gauge. In order to obviate such defects, an iron 

 permanent way has been designed by Mr. J. Cockburn-Muir, of Westminster. 

 The sleepers in this system have been specially desined for the Vignoles rail, 

 to which no altogether satisfactory application of a cast-iron support has 

 hitherto been made. The rail is held without bolts or nuts, so that it is not 

 weakened by punching. The form of the sleeper in plan is a parallelogram, to 

 insure the largest amount of bearing surface, while the corners are rounded 

 sufficiently to insure free flow of the metal in casting. The rail is held in posi- 

 tion on the inner side by two lips cast on the sleeper, and on the outer side by 

 a gripping-piece dropped in between the jaw on the sleeper and the foot of the 

 rail, the gripping piece, or clip, being brought home on the rail by a taper-key 

 of peculiar form, which is driven between the jaw and the back of the clip. 

 The transverse bar is of T-iron, the dimensions of which are regulated accord- 

 ing to the gauge and the weight of the engines to be used. 



With the view of obviating railway accidents, Mr. William Naylor has 

 recently introduced a continuous railway brake, which may be briefly described 

 as an adaptation of the ordinary lever waggon brake to the purpose of working 

 sets of brakes on a train of carriages. The levers which actuate the brake 

 blocks are connected by other short levers to a spiral spring, which is kept in 

 tension by means of a chain running under the entire train. When this 

 tension is released, which can be done at pleasure, the spring presses the 

 brake-blocks, through the action of the levers, against the wheels. Several 

 arrangements have been designed by Mr. Naylor for tightening the chain, but 

 want of space prevents further reference to the subject upon the present 

 occasion. 



A continuous railway brake, designed by Mr. E. D. Barker, of Weston- 

 super-Mare, is, we understand, about to be tried upon the Great Eastern Rail- 



