— 2M~ 
care is a fallacy. The unlimited duration of iron subjected to the shock of heavy 
and rapidly passing loads is not yefc proven, and experience lias sliown that tlie 
ironwork of bridges requires care and attention as thorough as does that of locoiuo- 
tives. 
Iron bridges should bo thoroughly inspected for rust spots at least once a year ； 
and， if any be found, the bridge should be repainted. One or two spots in places 
where something might have rubbed off tlie paint may be touched up with a lu ， usli ; 
l)ut， generally speakiug, when rust spots begin to appear, it shows that two go°^ 
coats of paint are required immediately. 
Tlio adjustable members should bo tested occasionally by tapping witli a ham- 
mer . This duty should not bo intrusted to an ignorant workman, wlio may turn 
away on tlie nuts until ho breaks the rods. Whenever, iu passing over a bridge, auy 
of the iron-work rattles, it shows that something is out of adjustment. Generally 
speaking, a well- proportioued iron bridge will not get out of adjustment unless so^ e 
one meddles with the nuts or turn buckles. 
The following extract from a paper 011 ‘‘ The Preservation of Iron Bridges ” by 
Mr. E. Paschen, a translation of which is given in tlie “ Abstracts of tlie Institution 
of Civil Engineers ” will givo some useful hints as to liow bridge inspection should 
be made. 
“Tlie Society of Architects at Berlin lias directed its attention to the qiiestiou ， 
and proposes that the railway companies generally should institute a system 
periodical inspections anti reports as to tho condition of their various iron bridges ， 
and recommends that the observations should be divided into two classes, the first 
(general) to be made in respect of every bridge, and the second in special instances 
only* 
‘ The general observations to be made every live years to include 一 
‘1. Measurement of permanent deflection. 
* 2, Measurement of deflection caused by loailiug (at rest). 
4 3. Enumeration of those portions of the structure and rivets 'vliicli 山町 
have already been renewed. 
1 4. Careful examination of plates at junctions of bracing with booms. 
* 5. Careful examination of paint and tlioso places affected by rust. 
‘ The special observations (to be made annually) to include 一 
‘6. Deflection of the lower flange under moving load. 
* 7. Distance apart of top and bottom flanges. 
‘8. Length of tho diagonals. 
* 9» Lateral distortion and vibration at the centre of tlie girders. 
‘All observations upon the stsucture when repeated, to be, if possible, made by 
the same inspector.’ 
In modification of tlie above the author suggests that the result of observation 
made by mere inspection should be kept separate from those obtained by loading , 如 
tlie former could be made at any time at a comparatively slight expense, and tl^ 
most important of the defects discovered, whereas the latter would necessitate tb 0 
presence of a sufficient number of engines of tlio heaviest class, and for the time be - 
