TREATMENT OF MANUFACTURED IRON AND STEEL. 285 
the holes in the joints are perfect and that there will be no 
trouble in re-erecting the structure at the site it is to occupy. 
If this is not done, complaints may be made by those who have 
charge of the completion of the bridge, which complaints are in 
many cases justified, but are seldom reasonable if the work has 
been carefully coupled together before leaving the maker’s hands. 
Manufactured Work. 
When the work has been manufactured and passed for accuracy 
of dimensions W&c., it should, if possible, have all the black oxide 
scale scraped or knocked off and be thoroughly cleaned before 
any paint is placed upon it. Many people stipulate that the 
plates shall be coated with oil before being manufactured into 
bridge work, &c., but in the author’s opinion this is a mistake 
unless such plates be exposed to severe oxidation during a long 
transit, such as from Great Britain to Australia. If the scale is 
not removed, no matter how good the paint may be, or how care- 
fully the work may be coated with it, some galvanic action will 
take place between the black oxide and the iren or steel, and the 
former will peel off, carrying with it all protecting coating that 
may be upon its surface. The importance of carefully removing 
this coating of oxide from iron and steel work manufactured in 
Great Britain for exportation, was mentioned to the author many 
years ago by our past Chairman of the Engineering Section of this 
Society, Mr. Darley, and it was found that there were fewer com- 
plaints made about faultily painted exported work, when it was 
allowed to weather during manufacture, until it could be effectively 
scraped before being painted. 
When the completed work has been temporarily erected at the 
manufacturer’s yard and carefully drawn together at the joints by 
correctly shaped drifts having but a slight taper at the points, the 
remainder of the body being parallel, well fitting service bolts are 
then used and all the work properly coupled up. Some specifica- 
tions stipulate that no drifting will be allowed, but practical men 
know that a, little drifting to bring the work properly together is 
very necessary, and in some cases good work could not readily be 
