22 



SCIENCE. 



[N. S. Vol. XVI. No. 392. 



bridge was used instead of the simple 

 truss bridge. 



A bridge is being built across the Charles 

 River between Boston and Cambridge that 

 deserves especial mention and marks a 

 decided advance in the growing recogni- 

 tion on the part of municipal* authorities 

 of the importance of esthetic considera- 

 tions in the design of public works. It 

 consists of 11 spans of steel arches whose 

 lengths range from 101^ to 188-J feet. Its 

 width is 105 feet between railings. It is 

 claimed that this bridge ' will be not only 

 one of the finest structures of its kind in this 

 country, but will be a rival of any in the 

 old world.' Its length between abutments 

 is 1,767^ feet, and it is estimated to cost 

 about two and a half millions of dollars. 



The problems incident to the replacing 

 and strengthening of old bridges frequent- 

 ly tax the resources of the engineer and 

 demonstrate his ability to overcome diffi- 

 culties. Only a few examples will be cited 

 to indicate the character of this work. In 

 1900 the Niagara cantilever bi-idge had its 

 capacity increased about 75 per cent, by 

 the insertion of a middle truss without in- 

 terfering with traffic. In 1897 the entire 

 floor of the Cincinnati and Covington sus- 

 pension bridge was raised four feet while 

 the traffic was using it. It may be of in- 

 terest to state that the two new cables, 10^ 

 inches in diameter, which were added to 

 increase the capacity of the bridge, have 

 just about three times the strength of the 

 two old ones, 12^ inches in diameter, 

 and which were made a little over thirty 

 years before. In the same year the old 

 tubular bridge across the Saint Lawrence 

 River was replaced by simple truss spans 

 without the use of false worlds under the 

 bridge and without interfering with traffic. 

 On May 25 of this year the Penn- 

 sylvania Railroad bridge over the Rari- 

 tan River and canal at New Brunswick, 

 'N. J., was moved sidewise a distance 



of 14^ feet. Five simple spans 150 feet 

 long and a drawbridge of the same length, 

 weighing in all 2,057 tons, were moved to 

 the new position and aligned in 2 minutes 

 and 50 seconds. The actual time that the 

 two tracks were out of service were respec- 

 tively 15 and 28 minutes. On October 17, 

 1897, on the same railroad near Girard 

 Avenue, Philadelphia, an old span was 

 moved away and a new one, 235 feet 7 

 inches long, put in exactly the same place 

 in 2 minutes and 28 seconds. No train 

 was delayed in either case. 



Henry S. Jacobt. 



COEXEI.L UnIVEESITT. 



REPORT OF PROGRESS OF THE NEBRASKA 

 STATE GEOLOGICAL SURVEY AND THE 

 MORRILL GEOLOGICAL EXPEDI- 

 TION OF 1901* 

 In spite of the phenomenal heat of the 

 summer of 1901, which was of such inten- 

 sity and duration that active work in the 

 field was iinally suspended, enough prog- 

 ress was made to justify the presentation 

 of the matter to this society. It should be 

 reported, first of all, that a request for 

 funds, amounting to twelve hundred dol- 

 lars, for publishing the first reports of the 

 state geological survey, was presented to 

 the Legislature, and was passed April 1, 

 1901, without comment or dissent. This 

 may be recorded as the first sum voted by 

 the state for the examination and publica- 

 tion of its resources; and, though small, it 

 is particularly large at this juncture, for 

 it makes possible the initial work of the 

 state survey. Unfortunately the passage 

 of the bill, by the Legislature, was a little 

 too late to enable us to avail ourselves of a 

 long-standing offer from the U. S. Geo- 

 logical Survey to cooperate in doing geo- 

 logical work in Nebraska, as soon as the 

 state evidenced its recognition of the im- 

 portance of a geological survey by offering 

 * Reported to the Nebraska Academy of Science, 

 January 25, 1902. 



