SCIENCE SIFTINGS

Wanganui Chronicle, Volume LXXXII, Issue 19365, 23 July 1925, Page 11

SCIENCE SIFTINGS

STEEL AND HOUSING It is interesting and instructive to 'compare the strength of steel with that of other materials and when this is ■ done it is seen that, weight for weight, I steel is thirty-four times as strong as [brickwork, fourteen times as strong |as plain concreate, twelve times aS (strong as masonry, land eight times as [strong as reinforced concrete. If the comparison bo made on the basis of ’area for area, the factor of brickwork (is 160, for plain concreate 64, for masonry 40, and for reinforced conicrete 26. This marked superiority of ’steel has far-reaching economic results, i Rapidity of erection is an obvious advantage to be gained from the adop Ition of steel-framed construction in [housing, and in many instances this (point alone is sufficient to mark out ’steel as the only possible material for [the problem in hand. So obvious is this [superiority that there is no need to labour it', but three recent achieveI meats may be quoted as typical examples. In the first instance a steel bridge having twenty-two main girders [ ■ whs erected over a railway line in the , j short space of five hours; in the seleond, the steel framing of a five | (storey building comprising 1600 tons | [of sections was completed in nine 'weeks; and finally another building, the | framing of which contained 400 tons ( of steel, was erected in only lour i weeks. Steel construction, therefore, [ allows building operations to be comipletod in the minimum time, and the 'site to be occupied and usefully employed at the earliest possible moment.

SHORT ELECTRIC WAVES. With the aid of very small Hertz oscillators cjpctric waves of only 0.22 mm. length have been produced which overlap the extreme infra-red rays of wave-length 424 u (or 0.424 mm 3 by an octave. The gap between long (light waves and short electric waves 'has thus been bridged over. The announcement of this achievement was to [have been made last summer in the [National Academy of Science, Wash[ington, bv Professor E. F. Nichols, [famous for his determination of the [radiation pressure of light in conjuncItion with Professor G. F. Hull in 1900 ■ (which followed the first determination bv Lebedeiew); but Professor Nichols died on the platform. The experiments I were described by his colleague, Dr. J D Tear, in the’ Astrophysical Journal of January. The Hertz oscillator 'consisted of tow tungsten wires, 0.1 ’mm. in diameter, projecting 0.1 mm. [from the glass tubes. The waves proIduced, had a length of 0.9 mm. and one of the overtones measured had a wave-

length of 0.22 mm. These waves passled through a quartz plate and a paraffin [lens to Im interferometer (mirrors or [an echelon built up of brass plates piled upon one another in step) and further to a receiver, a very fine platinum wire or a film of platinum, to meni sure the energy radiated in ti Hull ra[diometer. In other experiments in-Ifra-red mcrcnry-arc rays of wavelength 0.42 mm. were measured, slightly longer than those previously determinjed by Rubens and Hollnagel; the determination of still longer mercury (waves of 0.685 mm. was not quite cor (tbin, both figures would be in agree--1 ment with the quantum theory.—Engineering.