ENGINEERING. (TUNNEL OF GREAT NORTHERN RAILWAY, LUMBER FLUMES.) 285 



motives are constructed so that the shaft serves 

 as the axle of the locomotive, a device suggested 

 by the late Sir William Siemens, but not before 

 used in the British Islands. The locomotives 

 have a motor on each axle, and collect the cur- 

 rent through an ampere metre, returning it to the 

 rails through regulating and reversing switches, 

 magnets, etc., thus completing the circuit. Each 

 train will weigh about 30 tons loaded, and 10 

 trains can be worked at once. The construction 

 of the work has been under the charge of J. H. 

 Greathead, civil engineer 



Tunnel of the Great Northern Railroad 

 Company. Increasing traffic made it necessary 

 to construct a short tunnel, passing under some 

 of the heaviest business buildings and the busi- 

 est streets of the city of London. Some special 

 system of construction was necessary, in order 

 that traffic might not be interrupted. The plan 

 adopted was the invention of Messrs. Jennings 

 and Stannard. Instead of the ordinary timber 

 work used in tunneling, steel bars, technically 

 called "needles," were used; cross sections of 

 these are shown in the following illustration. 



TUNNELING-NEEDLES. 



Each needle is 10 feet long, 6 inches wide, and 

 2 inches thick, so arranged that when laid side 

 by side overlapping they admit free longitudinal 

 motion and can be adjusted to fit an arch of any 

 radius. When the initial excavation is made 

 the needles are inserted like ordinary tunnel bars 

 covering the crown of the arch. Brick work is 

 built up immediately under the needles, and each 

 needle can be forced forward by means of screw- 

 jacks. Longitudinal cavities extend through 

 the needles, so that grouting can be forced into 

 the spaces that are left as they advance. The 

 excavation is made exactly the size of the tun- 

 nel, plus the thickness of the needles. At King's 

 Cross Station the line ran under the freight 

 yard, only three feet of earth remaining between 

 the crown of the arch and the surface, on which 

 very heavy traffic was continually passing. Tun- 

 nels or drive- ways made after this manner are 

 less expensive, and, in many ways, more conven- 

 ient. For instance, in the case of sewers, the 

 exact shape can be made at once, instead of driv- 

 ing a square heading at first. 



Lumber Flumes and Chutes in California. 

 The enormous extent of logging operations in 

 the red-wood country of California has necessi- 

 tated a special system of engineering as these 

 magnificent trees disappeared from the imme- 

 diate neighborhood of the coast and the natural 

 water ways. No one can witness the reckless de- 

 struction of these superb forests without regret- 

 ting that improved systems of cutting, shipping, 

 and handling can be brought to bear upon them. 



The forests are disappearing so rapidly that two 

 or three generations may witness their extinc- 

 tion, unless wise legislation can be introduced in 

 time to save the red woods. Some of the engi- 

 neering operations are ingenious and interesting. 

 The country being very hilly, great care is taken 

 in felling the timber, and the enormous size of 

 the logs renders it extremely difficult to trans- 

 port them to a market. On entirely level ground 

 it does not pay to haul logs more than a quar- 

 ter of a mile, since it takes 12 or 14 cattle to a 

 log; moreover, a road must be prepared, and it 

 is usually cheaper to run a short railroad direct- 

 ly into the timber. This has been found to be 

 very expensive work in a hilly country, and 

 within a few years the construction of lumber 

 flumes has been largely introduced. These are 

 most extensively used in the northeastern part of 

 the red-wood district. The flumes are all con- 

 structed on what is known as " the V section." 

 They are made of boards, 20 inches wide, bat- 

 tened on the outside wherever necessary. The V 

 is 5 feet across the top and supported by ordinary 

 staging work, usually somewhat rough. The 

 flumes sometimes run for long distances at an 

 angle of as much as 45, but, in order to check 

 the rush of the lumber, it is necessary that a long 

 stretch of level flume should always "follow these 

 steep descents; in these the water reduces its 

 velocity to a manageable rate. A flume can be 

 built and put in operation at an expense of about 

 $5,000 a mile, though the cost is sometimes $15,- 

 000 a mile, according to the amount of timber 

 work and excavation. These flumes will carry 

 about 100,000 feet of lumber and 50 cords of 

 wood a day. For operating, one man is re- 

 quired for each 5 miles of flume, and a foot way 

 is constructed along the entire length. The 

 average speed of water approximates 5 miles an 

 hour. 



One of the largest flumes now in operation is 

 known as the 60-mile flume, near Chico, Cal. It 

 is constructed substantially on the plan indicated 

 above. As an accessory to the flumes, chutes are 

 common, especially on those sections of the coast 

 where it is impossible to load vessels from the 

 wharf. In many instances, indeed, there are no 

 harbor facilities whatever along this coast, nor 

 is it possible to construct them without great 

 expense. The presence of dangerous rocks com- 

 pels vessels to anchor several hundred feet off 

 shore, and the ceaseless swells that roll in from 

 the Pacific further complicate the problem of 

 safely delivering large logs from the high bluffs 

 of the shore. The stationary work of the chute 

 generally extends two or three hundred feet from 

 the land, with an attachment called an apron 

 extending from 40 to 90 feet farther. The chute 

 proper is constructed on lofty timber underpin- 

 ning, with guys reaching in either direction, and 

 anchored to the shore in order to prevent dan- 

 gerous swaying from side to side under the influ- 

 ence of the breaking sea. The apron, so-called, 

 is made fast to the end of the chute by very 

 heavy hinges and by guys extending to supports 

 built upward from the main scaffolding. The 

 guys are arranged as running rigging passing 

 over blocks and raising or lowering the apron, ac- 

 cording to the condition of the sea or the height 

 of the tide. The apron is usually held at the 

 height of 5 or 10 feet above the rail of the ves- 



