July 5, 1889.] 



SCIENCE 



whereby the route from Lake Huron to Lake Superior will be con- 

 siderably shortened and generally improved. 



A project is now being agitated, contemplating a direct connec- 

 tion between Lake Superior and Lake Michigan across the narrow 

 portion of the peninsula between Marquette and Escanaba, where- 

 by the passage through the Sault Ste. Marie would be entirely 

 avoided, and much distance saved for the traflfic between Lakes 

 Superior and Michigan. 



In the extension of the river-walls in New York harbor, under 

 the Department of Docks, large concrete blocks are being used, 

 weighing from 60 to 75 tons, and requiring hoisting-machinery of 

 extraordinary size and power to place them in position. Similar 

 blocks are being placed in the walls along the lake-front in Chicago, 

 where they have been found to resist effectually the action of the 

 waves in places where all former methods of protection have failed. 



Railroads. — Sixty years ago railroads were unknown in this 

 country. At that time the population of the United States con- 

 sisted of 12,000,000 people. To-day we operate 160,000 miles of 

 railroad, and our population has increased to 60,000,000 people. In 

 1830 the aggregate wealth of the United States was less than 

 $1,000,000,000: at present it is estimated at §56,000,000,000. Just 

 how much of this phenomenal prosperity may be due to the rail- 

 roads, it is, of course, impossible to conjecture ; but it may be safely 

 assumed that they have very largely contributed to the result. 

 While the population has increased during the last fifty years about 

 350 per cent, the ratio of increase of the railroad mileage for the 

 same period has been nearly four times that of the population, 

 which would seem to indicate that they have not only supplied a 

 want of the past, but have kept well up with the contemporaneous 

 growth of the country, if they have not, indeed, advanced beyond 

 its actual necessities. The railroad mileage of the United States 

 is now fully one-half that of the total railroad mileage upon this 

 globe, while our population is only about one-twenty fourth part, 

 and our area of territory only about one-twentieth part, of that of 

 the inhabited world. 



You have all heard the familiar illustration about girdling the 

 equator a dozen times, more or less, with our railroad-tracks ; but 

 it will no doubt please you to know, that, since you heard the state- 

 ment last, enough additional rail has been laid to give the equator 

 another twist ; and I might further supplement the illustration by 

 the assurance that we have now a sufficient supply of materials in 

 the tracks of this country to build a railroad to the moon. Over 

 these 160.000 miles of railroad we carried last year 475,000,000 

 people, and transported 600,000,000 tons of freight, Upon these 

 lines are engaged 1,000,000 employees. Their equip.ment con- 

 sists of 30,000 locomotives, 21,000 passenger-cars, 7,000 baggage- 

 cars, and r,ooo,ooo freight-cars. The capital invested in their con- 

 struction and equipment amounts to $8,000,000,000, and the yearly 

 disbursements for labor and supplies exceed §600,000,000. 



The creation of these vast properties has been accomplished by 

 aggregation rather than by preconcerted systematic development. 

 The trunk lines of the present day are to a great extent composed 

 of pieces of road originally built by local enterprises, and absorbed 

 from time to lime by lease or purchase, to constitute with other 

 acquisitions, in connection with some specially constructed con- 

 necting links, the various systems under the management and 

 control of the leading railroad companies of the country. 



The recent revival of the temporarily abandoned Hudson River 

 Tunnel project, and the proposed tunnel under the river at Detroit, 

 are enterprises demanded by the necessity of continuous transpor- 

 tation lines for the through traffic of our railroads. 



The numerous accidents which happen at points where public 

 highways cross the railroads at grade, in spite of alarm-bells, 

 watchmen, and safety-gates, have led to the enactment of laws in 

 some of the Eastern States looking towards a gradual abandon- 

 ment of existing crossings and the absolute prohibition of new ones 

 in the future. During the years 1887 and 1 888 there were abolished 

 in Connecticut 93 grade-crossings, at a cost of $625,000. In 

 Massachusetts a special committee of the Legislature has recently 

 reported upon this subject, recommending that all dividend-paying 

 roads eliminate annually 5 per cent, and all non-dividend-paying 

 roads i\ per cent, of their grade-crossings at the joint expense of 

 the railroads and communities, and that in future no grade-cross- 



ings shall be permitted. It is to be hoped that the beneficial re- 

 sults of these wise measures will induce other States to take this 

 subject under serious consideration. 



The most noteworthy engineering feature in connection with the 

 general progress of railroad construction in this country is the 

 building of bridge structures upon a constantly increasing scale. 

 In 1862 I triangulated the positions and laid the foundations for 

 the piers of the channel span of the Ohio River bridge at Steuben- 

 ville. This was the first iron railroad-bridge over any of the 

 navigable tributaries of the Mississippi River. The length of its 

 channel span vv'as 320 feet, and it was the longest iron truss ever 

 attempted up to that time. It was designed by Mr. J. H. Linville, 

 still a member of this society ; and it has carried in safety, and 

 without accident, the traffic of one of the principal Western con- 

 necting lines of the Pennsylvania Railroad for twenty-five years, 

 and is now being replaced by Mr. Henry G. Morse, also a m.ember 

 of this society, giving way to a double-track structure. To- 

 day twelve railroad-bridges span the Ohio River between Pitts- 

 burgh and Cairo, and two more are in progress of construction. 

 There are fourteen railroad-bridges over the Mississippi, and fifteen 

 over the Missouri. Many of these structures have spans of 500 

 feet, and one of the projected bridges over the lower Mississippi 

 was designed with a span of 730 feet ; but this plan, I understand, 

 has been abandoned, and a cantilever structure adopted in its 

 place. 



The erection of these large bridges has become a special business 

 in this countr)', and the leading contractors engaged in that pur- 

 suit have acquired wonderful skill in the performance of this dan- 

 gerous and difficult work. Few people appreciate the risks and 

 hardships encountered, and the courage and judgment required, in 

 dismantling an old railroad-bridge and erecting a new one in its 

 place, v;ith a deep and rapid river running underneath, a strong 

 wind blowing, and a hundred trains passing daily over the frail, 

 temporary supports, which must carry the traffic during the re- 

 placement. The mere erection of entirely new structures, free 

 from the encumbrance of moving traffic, is considered an easy job. 



In October last, the contractors engaged in the erection of the 

 bridge at Cairo swung free and clear a 520-foot span in six days, 

 and in November last the same parties erected the trusses of an- 

 other span of 520 feet length in 44 hours, and more recently they 

 erected a 400-foot span in 31 hours, the wind blowing a gale nearly 

 all the time. 



The successful completion during the past year of the Hudson 

 River cantilever bridge at Poughkeepsie reflects great credit upon 

 the builders and engineers in charge ; and the equally successful 

 completion and skilfully conducted erection of the Hawkesbury 

 Bridge in New South Wales adds new fame to the same firm of 

 contractors, whose leading partners are all prominent members of 

 this society. 



Whether the limit of possibilities in bridge construction will be 

 reached in the execution of -Mr. Gustav Lindenthal's design of a 

 railroad suspension-bridge over the Hudson River, with a span of 

 2,800 feet, resting upon towers 500 feet high, and carrying, in addi- 

 tion to wagon-vi'ays and foot-walks, six railroad-tracks, at a height 

 of 150 feet above water; or whether the projected crossing of the 

 British Channel will require still larger dimensions, — are problems 

 which may perhaps interest at some future day the younger mem- 

 bers of this society. 



NOTES AND NEWS. 



According to an ancient superstition, says Garden and 

 Forest, the beech is never struck by lightning ; and so general has 

 been this belief, that a gentleman recently thought it worth while 

 to write to an English journal that he had been told of a lightning- 

 shattered beech in Ireland. Beliefs of this sort are rarely without 

 some degree of justification in fact, and it would be interesting to 

 know whether in this country the beech has been observed to pos- 

 sess any greater immunity from electrical dangers than trees of other 

 sorts. 



— The Gardeners' Chronicle says that the gingko is proving it- 

 self one of the best trees for street-planting in smoky cities, thriving 

 in the most impure atmospheres, and having as yet been attacked 



