For a railway company, the most satisfactory method of building bridges is either to have a permanent, competent bridge engineer in its employ, or to retain some specialist of established reputation to prepare specifications and complete detailed plans (not working drawings, however) for all its bridges, and to provide competent inspectors to see that during manufacture, shipment, and erection the plans and specifications are strictly followed.

The necessity for the specialist to stand between the purchaser and the manufacturer of structural steel is, as a general rule, not appreciated by the purchaser, unless he has already had some experience in letting contracts for and in the building of steel structures without engineering aid in the designing and supervision. When the purchaser puts himself in the hands of the manufacturer, he is pretty sure to get the worst of it; for if the contract be let by schedule prices the structure is liable to be loaded down with useless metal, while if the contract be let for a lump sum the structure will probably be ruined by having the metal "skinned" out of it, especially in the most important parts, viz., the details. Moreover, the manufacturer is seldom capable of evolving a truly first-class design, for the reason that his training has always been in the line of his own pecuniary interests, which are to obtain the maximum of pay for the minimum of structure; so that, even when given all the metal and money that he could ask for when preparing a design, he would not succeed in making a really good one, simply because of not knowing how.

On the other hand, the specialist should stand between the contractor and the purchaser, so as to see that the latter does not take any undue advantage of the former by means of a harsh or unjust interpretation of the specifications, especially when the contractor has suffered loss or delay on account of causes beyond his control.

Occasionally a manufacturer offers to prepare the plans for certain portions of the work on the plea that he has had so much more experience in such matters than the engineer. The acceptance of this offer by either the purchaser or the engineer is a mistake;  for the engineer,  if  he  have  sufficient  ability to