New Instruments of Precision

1915 Scientific American  
will not pass through air, although they will through fl uorite and partly through quartz. It produces small ions of both signs, neutral centers, large ions, and ozone. It is extremely lIensitive to minute traCes of im purities in the gas, traces which cannot be detected by other means. It can be distinguished from the Hertz effect and become very much greater: All these conclu sions are drawn from the researches of Hughes,", Can negieter,71 Lenard and Ramsauer,", and Leon and II]ugene Bloch.19
more » ... The latter have shown also that the ra diation transmitted by quartz and coming from a mercury arC ionizes the air feebly in the neighborhood of the arc and seems consequently to emit a small amount of Schumann rays. In place of the usual source of Schumann rays, a hydrogen tube furnished with quartz windows, Lenard and Ramsauer used a very powerful spark between electrodes of aluminium. Then the ionization takes place even through air and quartz and the experimenters attribute it to rays of wave length less than 0.1 Itlt, the smallest ultra-violet rays lmown, and which were discovered by Lymann. As no measure of these wave-lengths was made, it seems as probable that the effect is due to ordinary Schumann rnys which have been partially transmitted by media generally opaque to them because of the great original intensity of the light. This question remains to be studied as well as the Lenard effect in general, the knowledge of which is yet very limited despite the great number of interesting problems connected with it. of Architect ure, Columbia University THE question is frequently asked, Will America ever develop a style of architecture? Probably the nearest we have come to it is in the erection of the skyscraper -the most striking and characteristic feature of Ameri can architecture-although this is but a step in the development. The demand for the skyscraper is an outcome of con ditions peculiar to New York, although Chicago claims the honor of having erected the fi rst steel skeleton build ing. Manhattan Island is so narrow and its trade center is so near one end that the rapid increase in trade since 1870 has necessarily been confi ned in a limited area, and in consequence the land there has advanced rapidly in value. The fi rst direct result of the menace in the height of buildings was the invention of passenger elevators for commercial buildings, for it was soon discovered that tenants would not mount stairs above four, or, at the mosl, fi ve stories. Elevators were employed for the fi rst time in the Fifth Avenue Hotel in 1856, and later on, in 1868, in the old Equitable Building, destroyed by fi re in 1911. The gradual development and improvement in high speed made vertical travel easy and comfortable, and the erection of six, then seven, eight, and fi nally nine-story buildings became possible. So that the prob lem of making downtown real estate investments profit able was thus temporarily solved. As years went on, however, even nine-story buildings in which the cheapest offices rented for $2 per square foot of fl oor space ceased to yield sufficient revenue, owing to the constant rise in real estate values, so that the height of buildings had to be raised to ten and twelve stories. It was soon discovered that these tall buildings, constructed as they were of combustible mate rials in the fl oors, stairs, and elevator wells, could not be controlled in case of tire, so the Building Department in 1882 passed a law requiring buildings exceeding eighty-fi ve feet in height to be fjreproof. This gave a great impetus to steel construction, and buildings such as the Mills, Morse, and Post were erect ed, in which, for the lirst time, the fl oor beams and interior columns were made of iron or steel. The further development of steel construction made it pos sible to erect a safe and economical building rising to a greater height. A new difficulty here presented itself. Under the old system of construction the outer walls became so thick at the base, when the building was carried up twelve or lifteen stories, as to cause a loss of income to the owner, as, on a narrow lot, little more than an entrance hallway would be left. It became necessary to make the walls thinner, and this resulted in the construction of curtain walls and skeleton frames. The masonry walls are not needed for strength;, they are divided into sections and supported by the steel frame. A twelvc-Htory building, for instance, would require 36-inch bearing walls on the fi rst fl oor, but only 20-inch skeleton walls, saving nearly three feet in the width of the building, or over 10 per cent on a lot 25
doi:10.1038/scientificamerican06051915-368bsupp fatcat:csjzvvjofbeybpvswix4mvr7o4