NATURE 



409 



THLfRSDAY, AUGUST 23, 1906. 



TUNNELS AND TUNNELLING. 

 Modern Tunnel Practice. By D. McNeely StaufTer. 

 Pp. vlii + 314. (1-ondon : Archibald Constable and 

 Co., Ltd., 1906.) Price 215. net. 



THE authcir of this book is to be congratulated 

 both upim havinf^ produced what ■ will prove 

 to be a useful book of reference for en|j^ineers engajjcd 

 in the arduous work of tunnelling-, and also upon the 

 fair and impartial manner in which he writes. He 

 has g^iven credit to those men whose names are asso- 

 piated with certain great improvements, and has not 

 .•itlcmpted, as is sometiines unfortunately the case, to 

 claim inventions for his countrymen which rightfully 

 belong to English, Italian or other nationalities. 



.Mr. .Stauffer is an .Xmerican engineer in New York, 

 but he is also enrolled as a member of our Institution 

 of Civil Engineers of London, and it is evident that 

 he has had considerable and practical experience of 

 the dilViculties of tunnelling. 



Naturally tunnels are things to be avoided as being 

 both costly and difticult, but for penetrating moun- 

 tains, crossing under rivers and arms of the sea, or for 

 traversing our great towns and cities, they are indis- 

 pensable. There is, however, one well-known case 

 of a tunnel in South .\merica in which the engineers 

 deliberately ran their railway into a mountain in order 

 that their countrv should not retain the notoriety, 

 undesired by them, of not possessing a single work 

 of the kind, and over the portal of that tunnel is 

 marked in large letters, " This is the first tunnel in 

 the country." 



The illustrations are good and brought down to a 

 recent date, but they unfortunately suffer from the 

 one defect that the dimensions and notes of reference 

 are almost too small to be read except with the aid of 

 a magnifying-glass ; it is a recognised principle that 

 drawings which are to be reduced for publication in 

 the leaves of a book should have all the writing and 

 figures several times the usual size, so as to be easily 

 legible when reduced. 



The chapter on surveying for tunnels contains the 

 latest practice, and will be useful to all students and 

 young engineers. The author describes how a ray 

 of light is now used in many cases in place of wires, 

 but where the latter are still employed the inconveni- 

 ence resulting from their acting as long pendulums 

 is overcome by suspending the plummets in buckets 

 of water; tar, with its greater viscosity, is, however, 

 more certain in its action, but has the drawback of 

 being easily floated out by water falling down the 

 shaft. 



The use of explosives is gone into verv fullv, many 

 of the various kinds being described, with rules for 

 their handling and thawing in cold weather; the 

 general principles of blasting and the position and 

 depth of bore-holes are carefully explained. 



It is found by experience that when driving a head- 

 ing or gallery through hard material, more rapid 

 progress is made if a wedge-shaped mass of rock be 

 blown out first, in the centre of the work, as by so 

 NO. 1 92 I, VOL. 74] 



doing the excavation round the margin of the tunnel 

 section is more easily removed to a true line. This is 

 elTected by making the centre holes converge to a 

 |X)int, and charging them in such a manner, by 

 shortening the fuse, that their charges will be fired 

 a few seconds earlier than those in the rem.iining 

 holes. Useful hints are given as to the precainionary 

 measures to be taken in case of :i misfire, when a 

 charged hole has to be bored out. 



The effects upon the engineers and workmen from 

 the products of combustion of the explosives are re- 

 ferred to, and instructions are given as to remedies, 

 but the principle of ample ventilation right up to the 

 very face of the work cannot be too strongly insisted 

 upon. If large volumes of fresh air are provided for 

 the men in the most advanced working, no danger of 

 asphvxia is to be feared. 



The introduction of high explosives, powerful drills, 

 and ample machinery has reduced the necessity for a 

 large number of shafts, and work is now often con- 

 ducted only from the two portals. The author dis- 

 cusses from a practical point of view the size and 

 shape of .shafts when required, and is of opinion that 

 those of rectangular form are preferable to either 

 square or circular ones. Doubtless there is much to be 

 said in favour of his views, but if water be encountered 

 in a shaft and has to be "tubbed out," the circular 

 is the only permissible form. .As regards the actual 

 sinking through water-bearing strata, compressed air 

 cannot be made available under a greater " head " 

 than 100 feet. Pumping can be resorted to, as is 

 usually the case, or the " Kind-Chandron " method 

 of sinking, as was done at Whitburn, whilst the more 

 modern system of freezing has been tried with success 

 recently in one or more of the collieries in Durham. 



It is, however, costly, and has its own inherent 

 dangers which must be provided against ; for instance, 

 a case recently occurred in which the frozen material 

 gave way under the hydrostatic head of the water 

 behind it, and blew in the side of the shaft. 



The various methods of tunnelling known as the 

 English, the Belgian, the German, and the .Austrian 

 systems are described, and it is satisfactory to note 

 that the Americans adopted the first of these in several 

 of their important tunnels. The use of steel needles 

 in a London tunnel under houses is referred to, but 

 notwithstanding every possible care and precaution, 

 some injury was done to the property; now, however, 

 by the adoption of the shield, this is reduced to a 

 minimum. 



It is satisfactory to observe that the author gives 

 the credit to the late Mr. Greathead of his shield, for 

 although he was not the actual inventor, yet it was 

 he who so modified and introduced it into practical 

 work that it has been universally adopted by the engin- 

 eering profession as the solution of much of the 

 difficulty encountered in tunnelling. In like manner 

 the name of Signor Saccardo is given as having 

 invented the admirable system of ventilation with 

 which his name is connected, although in more than 

 one case in .America his proposals have been adopted 

 without his name even being mentioned. 



The important tunnels in Paris, Budapest, Boston, 



