Alu examination of the drawings and strain sheets submitted, by the firms enumerated, shows that considerable divergence of opinion still exists as to what is mioaiit by the teri "best modern practice"
teed' mh th ication of the Engineer in Chief, "Tio ated July 16th, 1891, In every instance however, except in the Belgian designs, the working stress on the girdersof the floor system was less than that on the main girders, and regard was) had generally tothe fact that where the rolling is considerable in proportion to the dead load, the stress should be correspundingly reduced Is was in the mode of dealing with the wind stresses that the greatest divergence ied.
ome cases the resultant stresses were added to those due to the dead load and the rolling load and the sectional areas were proportioned thereto. In other cases no additional sectional area was provided as it was assumed that if the sectional arcus were sufficiently large to withstand the constant passage of heavy rolling loads year after year, they would also be sufficient to withstand the additional stress of an occasional hurricane, As result, in some designs of 200 feet girders the effectual sectional wren of the top member w: equal to that of the bottom member others it was 15 per cent. less, and in in, differences existed ea to the mode 5 per cent. ter. ing the wind stresses cases provision being made for th posed surface of the leeward girder and for the overturning momentum of the wind on. th train, and in other cases riv such provision was made.
Te will be obvious therefore that the tenders submitted donot _ndmit of a direct comparison without previous careful revision of the designs to put them on the same basis as far as possible as regards strength and otherwise.
Having done this I found Messrs. Hundyoffer to be on the whole the most waurable.
The 200 feet spans required in my opinion certain re-adjustments of the sectional areas given to different parts of the structure, but no increase of the total weight of steel: work. The 100 feet spans required similar re-adjustments, and an increase of 5 per the weight of steelwork.
Messrs. Handyside's weights and priors thus become 808 tons and 66,200 taels for the five 200 feet spans and 365 tons and 29,452 taels for the ten 100 feet spans, and recommend the acceptance of their tender fon that basis, subject to the work being executed to my entire satisfaction in accordance with detailed drawings and specification to be approved of in writing by me previous to the signing of the contract and subject farther to the terms of delivery specified in Messrs. Handyside's letter to me dated November 17th being considered satisfactory.
With the at my suggest the bridge work will be well proportioned throughout as regards strength and durability and be capable of erection with the greatest amount of facility attainable, and the least amount of rivetting. All parts aleo will be easily painted.
Tam, Excellency, Your obedient servant, (Signed) B. Baxen,
Text read from the printed page and cleaned; old type leaves the occasional error.