As heat-treated, carbon-steel eye-bars have an elastic limit of 50,000 lbs. per square inch, the same as that for untreated Mayarí-steel eye-bars, and as the unit price erected is also about the same, the conclusions reached concerning the latter will apply also to the former.

As for heat-treated, Mayarí-steel eye-bars, the author has no data regarding their strength, nor is he convinced that the irregularity in the elastic limit of that alloy would not militate too strongly against using it in bridgework after heat treatment. Judging, though, from the computations which follow concerning heat-treated nickel-steel eye-bars, one would surmise that suspension bridges of heat-treated, Mayarí-steel eye-bars might be economical up to spans of 2,000, feet.

High-Grade Nickel-Steel Comparison.

1,000-Foot Span.

Eye-Bar-Cable Structure

2,000-Foot Span.

A comparison of these figures with those previously made for wire-cable structures shows that the high-grade, untreated, nickel-steel is economic for 1,000-ft. spans but not for those of 2,000 feet, hence let us test for an intermediate length.

1,500-Foot Span.

Wire-Cable Structure