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Solar house-warming
286
CURRENT TOPICS.
IJ. iv. I.
than a minute on any reasonably smooth surface such as metal, cloth or ceramics. For office duplicating, it will provide a 7,000-volt machine t h a t can be operated safely by a stenographer. For high-speed printing, lightweight Xeropresses will turn out 1,200 ft. a minute, as fast as any conventional press now running. Photographers will be able to make full color prints in one t e n t h the present time. The inventor, Chester Carlson, conceived of dry printing simply as a n easy means of small-scale duplicating. Exactly 10 years after his first print, Battelle Memorial Institute (Columbus, Ohio) and the Haloid Co. (Rochester, N. Y.) revealed spectacular applications in every phase of graphic arts. The method is simple: A layer of photoconductive material (sulfur) on a zinc plate is given a charge of static electricity. This plate is then exposed to a light source which passes through the "copy." Powder sprinkled on the resulting photoelectric image becomes charged only on the spots which the light did not touch; This powder image is then fused to the surface to be printed. While the process is still in the initial stages, there is no d o u b t t h a t Xerography has a tremendous future in store. Solar House-warming (Discovery, December, 1948).--A woman physicist, Dr. Maria Telkes of the Massachusetts Institute of Technology, has announced t h a t as far as she was concerned harnessing solar energy was practical, and t h a t within a few weeks she would move into a house whose sole sonrce of heat would be derived from the sun. At a cost of $20,000, of which $3000 was for the solar heating plant, the five-room one-story house will be completed in Dover, a town fifteen miles from Boston. The heating will be built into the roof of the privately financed structure, consisting of 800 square feet of black metal sheeting behind two glass plates acting as heat traps. Ducts circulate the air behind the metal sheets and when warmed is conducted to 'heat-bins' a t strategic points throughout the house. The bins are connected to registers, each serving two rooms. Warm air is blown from the bins through the registers into the rooms. Storage of heat in the bins is accomplished by utilizing a chemical--sodium sulfate dekahydrate--which melts as the heat is stored in it. When the chemical solidifies again, the heat is given off. Heat can be stored for as long as ten days, making possible comfortable warmth even on days when sun rays are" not available. The heating system costs nothing to operate, and the chemical lasts indefinitely. When questioned as to what she would do if the solar heating plant broke down during the winter, and if a conventional heating plant would be installed " j u s t in case," Dr. Telkes said emphatically t h a t she would rely solely oil her solar furnace and if it broke down she would shiver, "and it will serve me right." S m o k e T e s t e r (Instruments, Vol. 21, No. 12).--New hand-operated " T r u e spot" smoke tester is primarily for use in checking oil burners for clean firing. Smoke test is made by locking paper test disk into instrument, inserting metal probe into suitable hole in smoke pipe, and drawing with six pump strokes a sample of combustion gases from furnace flue. Disk t u r n s light to dark gray depending on smokiness of flame. Soot content is measured by comparing discoloration with nine shadings on scale supplied with instrument. Scale
CURRENT TOPICS.
IJ. iv. I.
than a minute on any reasonably smooth surface such as metal, cloth or ceramics. For office duplicating, it will provide a 7,000-volt machine t h a t can be operated safely by a stenographer. For high-speed printing, lightweight Xeropresses will turn out 1,200 ft. a minute, as fast as any conventional press now running. Photographers will be able to make full color prints in one t e n t h the present time. The inventor, Chester Carlson, conceived of dry printing simply as a n easy means of small-scale duplicating. Exactly 10 years after his first print, Battelle Memorial Institute (Columbus, Ohio) and the Haloid Co. (Rochester, N. Y.) revealed spectacular applications in every phase of graphic arts. The method is simple: A layer of photoconductive material (sulfur) on a zinc plate is given a charge of static electricity. This plate is then exposed to a light source which passes through the "copy." Powder sprinkled on the resulting photoelectric image becomes charged only on the spots which the light did not touch; This powder image is then fused to the surface to be printed. While the process is still in the initial stages, there is no d o u b t t h a t Xerography has a tremendous future in store. Solar House-warming (Discovery, December, 1948).--A woman physicist, Dr. Maria Telkes of the Massachusetts Institute of Technology, has announced t h a t as far as she was concerned harnessing solar energy was practical, and t h a t within a few weeks she would move into a house whose sole sonrce of heat would be derived from the sun. At a cost of $20,000, of which $3000 was for the solar heating plant, the five-room one-story house will be completed in Dover, a town fifteen miles from Boston. The heating will be built into the roof of the privately financed structure, consisting of 800 square feet of black metal sheeting behind two glass plates acting as heat traps. Ducts circulate the air behind the metal sheets and when warmed is conducted to 'heat-bins' a t strategic points throughout the house. The bins are connected to registers, each serving two rooms. Warm air is blown from the bins through the registers into the rooms. Storage of heat in the bins is accomplished by utilizing a chemical--sodium sulfate dekahydrate--which melts as the heat is stored in it. When the chemical solidifies again, the heat is given off. Heat can be stored for as long as ten days, making possible comfortable warmth even on days when sun rays are" not available. The heating system costs nothing to operate, and the chemical lasts indefinitely. When questioned as to what she would do if the solar heating plant broke down during the winter, and if a conventional heating plant would be installed " j u s t in case," Dr. Telkes said emphatically t h a t she would rely solely oil her solar furnace and if it broke down she would shiver, "and it will serve me right." S m o k e T e s t e r (Instruments, Vol. 21, No. 12).--New hand-operated " T r u e spot" smoke tester is primarily for use in checking oil burners for clean firing. Smoke test is made by locking paper test disk into instrument, inserting metal probe into suitable hole in smoke pipe, and drawing with six pump strokes a sample of combustion gases from furnace flue. Disk t u r n s light to dark gray depending on smokiness of flame. Soot content is measured by comparing discoloration with nine shadings on scale supplied with instrument. Scale