ENGINEERING IN 1892. 



251 



chain of lakes was connected with the sea. But 

 tin' engineering dilliculties peculiar to the rest of 

 tln> route postponed further operations until 

 1886. The Government then decided on its ac- 

 oomplisliiiifiit. and engineers mainly Norwe- 

 \ve believe have most successfully over- 

 come the difficulties. By nature the lakes were 

 connected by a considerable river, with frequent 

 rapids and falls, but this, by means of locks and 

 tlic other appliances familiar to canal builders, 

 has been cmm TI. >! into a navigable channel. 

 Thr greatest natural obstacle was encountered at 

 Drangfos, a succession of falls and rapids more 

 than a mile long and having a total descent of 

 about 75 feet. Here it was necessary to dam the 

 river at the foot of the incline and raise the 

 water to the height indicated. As the natural 

 foundation was untrustworthy, a massive stone 

 arch was built across the chasm, forming a base 

 for the great dam of masonry which now re- 

 strains the rush of water. This canal passes 

 through scenery of great wildness and beauty, 

 and it will no doubt become a favorite route for 

 tourists in this picturesque region. 



Drainage Works. Chicago's long struggle 

 with the question of water supply and drainage 

 has passed several critical periods within a 

 few years, but the coming Columbian Fair has 

 brought matters to a crisis, and it is determined 

 that a large drainage canal shall be opened from 

 Lake Michigan to an affluent of the Mississippi, 

 so that the drainage of the great city will liter- 

 ally be carried into the Gulf of Mexico instead 

 of being emptied, as heretofore, into the source 

 of the city's water supply. It has been held by 

 some geologists that m former ages the lakes 

 found their outlet to the gulf instead of to the 

 Atlantic. However this may be, it is certain that 

 the level of the Mississippi river opposite Chi- 

 cago is enough lower than the level of the Great 

 Lakes to insure an ample fall for drainage. The 

 beginning of the work has been made at the crest 

 of a ridge known as the Chicago Divide, on what 

 will be the central line of the main channel 

 intersecting the boundaries of Will and Cook 

 Counties. A deal of litigation is unavoidable to 

 decide upon the value of lands taken for the 

 canal, as well as upon consequential damages; 

 this, of course, in cases where tne owners and the 

 commissioners can not agree as to terms. Care- 

 ful estimates give $25,000,000 as a possible mini- 

 mum, and contracts amounting to about $11,- 

 500,000 have been let from Willow Springs to 

 Lockport. This estimate is for actual construc- 

 tion alone, not including the price of land, so 

 that it is extremely probable that the total 

 amount will considerably exceed the sum named 

 above, particularly when the almost uniform 

 tendency of engineers to underestimate is taken 

 into the account. The necessity of the work is 

 imperative, at whatever cost, and no doubt it will 

 be carried out with characteristic energy. The 

 projected canal, saturated as it must be with rich 

 but unsavory fertilizing material, is not without 

 its terrors for suburban residents ; but it holds 

 out, at the same time, attractive possibilities to 

 agricultural interests, and will no doubt eventu- 

 ally be utilized for that purpose. 



Sewerage is not a particularly savory subject, 

 but it is satisfactory to know that modern scien- 

 tific ingenuity is reducing its objectionable fea- 



tures, and even rendering it available for purpose* 

 that could hardly be anticipated. Recent exjM-ri- 

 ments in the vicinity of Berlin, Germany, are 

 among the most remarkable on record. Two years 

 ago, it is said, a pond having an area of about 

 1,000 square feet was supplied with water coming 

 directly from the sewerage system of the citT 

 after it had been employed for agricultural irri- 

 gation. The pond was stocked with trout, which 

 lived through the summer and winter until the 

 following year, when the water was drawn off 

 and 800 trout from 4 to 5 inches long were found. 

 The success of this experiment led to the con- 

 struction of six new tanks, with an area of more 

 than 40,000 square feet and a depth not exceed- 

 ing 8 feet. Some of these were stocked with 

 carp and others with trout, and at a banquet 

 lately given to Prof. Virchow about 150 of these 

 " sewer fish " were served in one of the courses. 

 Carp, it is well known, thrive in impure water; 

 but as trout are exceedingly fastidious in the 

 matter of water, the result at Berlin proves that 

 a process of filtration through wide cultivated 

 tracts is highly efficient. 



Relief Sewer in Brooklyn, N. Y. Warned 

 by a startling disaster involving loss of life and 

 considerable damage, the city of Brooklyn has 

 provided a sewer capable of carrying off the sur- 

 plus water of heavy rainfalls. The dangerous 

 district was about 1,300 acres in extent, and dur- 

 ing the first rush of water after a heavy rain the 

 lower streets were flooded, including adjacent 

 cellars, and much damage often resulted. The 

 work just completed is known as the main re- 

 lief sewer. It is carried across the drainage 

 area through Greene Avenue, Fourth Avenue, 

 and Butler Street to the head of the Gowanus 

 Canal, which falls into the natural cove now 

 mainly occupied by the United States Navy 

 Yard. With this main, the regular street sewers 

 are connected in such a way as to deliver only 

 storm water ; thus the regular sewers will only 

 be called upon to do work of which they are 

 amply capable. The tunnel has been made 

 under the Anderson method of construction, 

 using the Beach system of tunneling needles, 

 which is an American invention and was patent- 

 ed as long ago as 1869 by Alfred E. Beach, of 

 the " Scientific American." Recently, however, 

 it has been brought forward as an entirely 

 new thing in Great Britain, where it attracted 

 much attention from engineering authorities. 

 The needles are, in fact, heavy bars of iron 

 or steel. They are driven forward separately 

 into the earth that forms a support for the front 

 part, while the rear end rests on the progressing 

 work of the permanent tunnel. A notable in- 

 stance of the use of these needles at King's Cross 

 Station in London wasdescribed in the "Annual 

 Cyclopaedia " for 1890, page 285. The main part 

 of the sewer is circular in section, with a diame- 

 ter of 10 feet, enlarging successively to 12, 14, 

 and 15 feet as it descends, with walls usually 

 not exceeding 16 inches, except in some places 

 where local features call for a 28-inch side wall 

 Of this circular portion there are 11,400 linear 

 feet, of which more than IMKX) feet were laid by 

 tunneling, part of it far below the solidly built- 

 up parts of the city. Near the discharge end 

 the section is changed to something nearer a 

 rectangular form, the bottom being an inverted 



