--- title: Improvement Era description: Monthly periodical of the Mormon church, 1897 onward. This library holds the issues of November 1897 to December 1930. authors: - Snow, Chester collections: - periodicals tags: - magazine - improvement-era periodical: Improvement Era volume: 10 number: 3 published: 1907-01 publisher: Young Men’s Mutual Improvement Associations publisher_place: Salt Lake City language: en type: magazine reference: 'Snow, Chester, "Weighing the Earth," *Improvement Era* 10, no. 3 (January 1907): 214.' source: url: https://archive.org/details/improvementera1003unse transcription: Transcribed from the Internet Archive scan of each issue (the item for each issue is named in the issue's own source); unnumbered advertising leaves are omitted, printed page numbers are kept as page markers. identifier: improvementera1003unse start_page: 214 end_page: 214 rights: status: public-domain basis: US publication 1930 or earlier (published 1907-01) source: https://archive.org/details/improvementera1003unse publication_year: 1907 note: The Internet Archive item metadata carries a blanket "© Copyright by Intellectual Reserve, Inc." notice. The library owner judged it inapplicable because this issue was published in 1907, before 1931; a scan-level notice does not restore copyright. --- # Weighing the Earth 214 IMPROVEMENT ERA. upon plant growth. For this purpose hot houses were constructed of blue, green, red, and ordinary or white glass. The colorless glass allows the heat rays to pass through unob- structed, while the colored glass arrests and absorbs much of the heat. For this reason, on sunny days the temperature of the at- mosphere, in the house of ordinary glass, ranges about 5 degrees centigrade above that in the blue, 4 degrees centigrade above the green, and 2 degrees centigrade higher than the red. Plants grow tallest in the red light, and least in the blue. In the white light the plants are stocky and heaviest. Seeds also develop best in the ordinary sun light, but the blue light favors the development of more perfect flowers when the plants are placed in it just prior to blooming. Perfume is more abundant in flowers grown in red light. W. H. Homer, Jr., M. S. Weighing the Earth. In the last issue of the Era mention was made of the strenu- ous efforts made by several great physicists to measure accurately in the laboratory the force of attraction L etween two masses of ordinary magnitude. It has been found that two small spherical masses of one gram each with their centers one centimeter apart attract each other with a force equal to one fifteen-millionth of a dyne.* The importance of this knowledge, which may at first seem insignificant, can hardly be overestimated. It enables us to calcu- late the attraction, in known units of force, due to a great variety of other distributions of attracting matter. Since we know the force between two unit masses one centimeter apart, and since we know the law by which this force varies with the distance, we have at once a means of calculating the attracting force between any two spherical masses at any distance ap ; rt. Moreover, if we know the magnitude of one mass and measure the force of attrac- tion between the two, we can calculate the magnitude of the other mass. This immediately suggests a universal method of measuring * A dyne is defined as tnat force which, acting for one second on a mass of one gram originally at rest, will give it a velocity of one centimeter per second.