July 5, 1889 ] 



SCIENCE. 



special part of the profession with which the long-continued per- 

 formance of my official duties has afforded me opportunities to be- 

 come more familiar. 



Electrical Ejiginecrztig. — Of all the forces of nature, the one 

 which has remained a hidden mystery longer than all the rest, but 

 which of late has distanced all in the rapidity of its development, 

 and which is certainly destined to excel them all in the extended 

 range of its useful application, — electricity, — stands pre-eminent. 



In the prosecution of subterranean or subaqueous operations, 

 such as tunnelling, mining, sinKing of caissons, the use of electric 

 light is found to be of special benefit. In its incandescent form it 

 is absolutely safe against the dangers from explosive gases, and in 

 caisson work it removes the risks and inconveniences incident to 

 the ready and rapid combustion of inflammable substances under 

 the influence of high atmospheric pressure. 



Street-Railways and Rapid Transit. — The rapid growth of 

 our cities gradually forces the inhabitants to seek their homes in 

 the suburbs and surrounding country, more or less distant from 

 the business and manufacturing centres where their employment 

 lies. The desire for economy of time, and the necessity for punc- 

 tuality and prompt attendance, have led to the introduction of vari- 

 ous modes of conveyance, beginning with the street-car tramways 

 propelled by horses, followed more recently by elevated railroads 

 and cable-car lines, and still more lately by the electric railroad ; 

 which latter system has, within a few years, developed much more 

 rapidly than any of the preceding methods. 



At the close of the past year there were completed and in course 

 of construction, in this country, eighty-five electric railways, com- 

 prising about 450 miles of track, and the reports show that during 

 the last year over eighteen millions of passengers have been carried 

 over these lines. 



The cheapness of original construction and subsequent main- 

 tenance and operation commends their adoption in smaller cities, 

 where the older systems would be out of the question ; and the 

 practicability of their application in situations which would exclude 

 cable-lines and horse-traction has led to their introduction in 

 places like my own home, Allegheny City, where an electric rail- 

 way is now in successful operation, which, in a distance of one mile 

 out of a total length of four miles, ascends, with a speed of fully 

 four miles per hour, a hill over 400 feet high, upon gradients of i2| 

 per cent, with numerous curves of 40 feet radius, the cars being 

 often loaded with 75 people. Upon the lower portion of this line 

 the electric current is supplied by means of an underground current, 

 and on the upper portion of the line by the ordinary overhead con- 

 ductors. 



But while undoubtedly the electric railway will be generally pre- 

 ferred in the immediate future, it is by no means to be inferred that 

 the cable-lines are to be considered as the motors of the past. On 

 the contrary, their use will not only be continued, but greatly ex- 

 tended, wherever the conditions and circumstances favor their 

 adoption. Among the advantages which they possess, are uni- 

 formity of motion, generally satisfactory speed, and the ease with 

 which, in times of heavy travel, the vehicles can be multiplied and 

 combined into convoys ; and the facilities which they afford to con- 

 verging horse-car lines, whose carriages they can attach to their 

 own at the points of junction, saving thereby transfer of the pas- 

 sengers. The machinery used at the power-houses of some of the 

 principal cable-lines is of very superior character, and some of the 

 details employed are models of skill and ingenuity. Noteworthy 

 among these are the engines of the Brooklyn Bridge cable-line, 

 which many of us admired during the excursion at the time of the 

 last annual meeting, and which are very interestingly described n 

 a recent contribution to our " Transactions " by Mr. Gabriel Lever- 

 ich, one of our members, and at one time secretary of this society. 



Elevated railways propelled by steam must necessarily remain 

 confined to larger cities, where the volume of traffic promises a re- 

 turn for the capital invested in their expensive construction, and 

 where the distances to be reached are sufficiently great to make the 

 saving of time, by means of their superior speed, an inducement 

 for patronage. 



Water- Works. — The introduction of water-works is now so 

 extensive in this country that there are but very few cities or towns 

 of more than five thousand inhabitants which are not supplied with 



one system or another. The beneficial results upon the health of 

 the populations are universally recognized, and the sanitary bless- 

 ings and the advantages in point of comfort are beyond all calcula- 

 tion. Wherever additions and changes become necessary in the 

 older cities, wise precautions are generally taken, under the advice 

 and direction of professionally skilled experts, to profit by former 

 lessons, and to avoid the errors of the past. 



The most extensive enterprises now in progress in connection 

 with water-works extensions are the improvements embracing the 

 new lake tunnels at Chicago and Cleveland, the new Croton Aque- 

 duct in the city of New York, and the aqueduct extension in Wash- 

 ington, D.C. In all these cases the question of greater purity has 

 been carefully considered in connection with the increased supply. 



The collection and storing of water-supplies for large cities and 

 manufacturing purposes require, in many cases, the construction of 

 extensive reservoirs, with massive dams for the retaining of the re- 

 serve supply. The importance of constructing these dams of 

 proper shape and size, and of suitable material and good workman- 

 ship, so as to insure their absolute strength, and give them suffi- 

 cient resisting capacity against every possible contingency, has been 

 taught by a recent lesson of frightful experience; and while the 

 responsibility for this calamity may not be placed upon the shoul- 

 ders of the profession, yet it will be well for its members to look 

 upon it and remember it as a warning and an example. 



An investigation of the cause of the failure of the South Fork 

 dam is now being made by a committee appointed under a recent 

 resolution of this society, who have just returned from a visit to the 

 scene of the disaster. 



Examinations and measurements of the structure and its sur- 

 roundings, and extensive information obtained from various sources, 

 will enable the committee to submit to the society in due time a 

 comprehensive statement of the conditions and circumstances 

 which have induced and contributed to this most disastrous fail- 

 ure. 



Sanitary Engineering. — The extensions and improvements of 

 the water-supplies of our cities naturally lead to the adoption of 

 measures for the disposal of sewage. The respective merits of the 

 different methods employed for this purpose have been very ably 

 presented to the profession from time to time, in occasional con- 

 tributions to our " Transactions," by several members of this so- 

 ciety, who stand pre-eminent in their special calling ; so that all 

 that would now seem necessary in an emergency is the exercise of 

 sound and impartial judgment in the adoption of the proper method 

 for each special case. 



The system most generally used in this country now, and which 

 will no doubt be preferred for a long time to come, is that of com- 

 mon water-carriage by means of the so-called " combined " plan 

 of discharging all sewage and storm-water together through com- 

 mon outlets into adjacent rivers, lakes, or tidal waters. The ob- 

 jectionable features of this method consist in the pollution of the 

 streams and lakes, from which, in turn, the water-supply may have 

 to be drawn ; and the injurious effects caused by the deposit and 

 periodical exposure of offensive matter upon the shores of tidal 

 waters. 



In order to overcome, at least partially, these objectionable fea- 

 tures, modifications of this method have been tried, consisting in a 

 filtration and chemical purification of the sewage so as to reduce 

 the offensive portions, and to render their final deposit into the 

 streams of the district comparatively harmless. The methods em- 

 ployed for some time at Pullman, III., and more recently at Orange, 

 N.J., are samples of this system. 



Under the provisions of a law passed by the Legislature of 

 Massachusetts in 1886, the State Board of Health is authorized to 

 investigate, through a commission of experts, the effect of sewage 

 discharge upon the streams and inland waters of the Common- 

 wealth, and to recommend to the courts annually plans in remedy 

 of existing evils. Acting upon the reports of this board, several 

 cities are now making preparations for the disposal of their sewage 

 by various methods of purification and dilution. In connection 

 with some of these systems, the fluid portion of the sewage is util- 

 ized as a fertilizer of farm-land. 



By the general introduction of natural gas as a domestic fuel in 

 Pittsburgh and other Western cities, a large amount of kitchen- 



