On Chain Bridges. 



371 



Talle of the mean Height of the Barometer in ISIT* 



Montlis. 



1"^ "I 



't 

 January . 



^February . 



IMarch . . J 



'April ... J 



May . . . .1 



Jane . . . .' 



July i 



jAugnst . .{ 



jSeptemb. I 



October . . 



November 



December 



9 A.M. 



in.ni. 



752,Gl 



756,71 



753,88 



749,92 



753,50 



755,21 



751,22 



756,70 



756,21 



754,37 



753,52 



755,63 



Mid- day. 



P. M. 



Averages. 754,13 



752,19 

 756,7 i 

 753,79 

 749,64 

 753,40 

 754.94 

 751,05 

 756,29 

 756,11 

 754,15 

 753,64 

 755,46 



753,94 



752,06 



755,92 



753,02 



749,06 



752,96 



754,56 



750,67" 



755,68 



755,66 



753,39 



753,53 



754,95 



9 P. M. 



752,16 

 756,21 

 753,27 

 749,18 

 753,51 

 754,62 

 750,91 

 756,03 

 756,35 

 753,68 

 754,03 

 755.12 



753,45 



753,76 



JMiscellaneous Remarks. 

 During this year there have been at Paris 167 days of raitlj 

 13 of snow, 19 df hail, 71 of frost, and 10 thunder-storms. Ihe 

 u-ind has l,loun from the north 12 days ; from the north-east 51 ; 

 from the east 24 3 from the south-east 24 ; from the south 52 ; 

 from the south-west 83 5 from the west 84, and from the north- 

 west 36. 



LXXXVII. On Chain Bridges. Bij A Correspoxdent. 



The proposed bridge at Pauicorn having greatly excited the 

 attention of the public, and the consideration of mathematical 

 and mechanical men, who seem to differ considerably as to the 

 principles as well as the construction of a chain bridge j for the 

 information of persons immediately interested, and those who 

 have curiosity and ability to prosecute these inquiries, I have 

 toUected into one point of view all the essential parts of thi3 

 difficult subject, by which calculations may be made, and with- 

 out which no project of this kind, however plausible, ought to 

 be entertained. 



It is too evident to need demonstration, that if a cliain con- 

 sisting of a number of connected links be suspended by one of 

 its extremities, the lowest link will suffer the least strain, the 

 next link will be drawn bv its own weight, and that immediately 

 ' A U 2 below 



