Popular science monthly . ctors of simpledesign are shown in the of Fig. 2 is made by solderingbinding posts, obtained from the zincshells of old dry cells, to a piece of sheetmetal as shown. Fig. 2 shows one ofbetter electrical design in that allconnections are soldered. Both will befound serviceable.—E. R. Thomas. An Unusual Code Letter EXPERIMENTERS who listen tomessages passing to and fromGerman or Spanish stations are oftenpuzzled by the code-letter of fourdashes. This signal represents thecombination CH and is used as asingle letter in the International Morseor Continental


Popular science monthly . ctors of simpledesign are shown in the of Fig. 2 is made by solderingbinding posts, obtained from the zincshells of old dry cells, to a piece of sheetmetal as shown. Fig. 2 shows one ofbetter electrical design in that allconnections are soldered. Both will befound serviceable.—E. R. Thomas. An Unusual Code Letter EXPERIMENTERS who listen tomessages passing to and fromGerman or Spanish stations are oftenpuzzled by the code-letter of fourdashes. This signal represents thecombination CH and is used as asingle letter in the International Morseor Continental code. Four dashesforming one character in AmericanMorse signify the beginning of a newparagraph. Continued practice alonewill clear up the confusion on this point. Mounting a Rotary-Gap THE noise made by the \ibrations ofthe rotary-gap can be reduced toa minimum by cutting hollow rubberballs in half and placing them under therotary-gap as shown at A A in theillustration. The sound will be greatlyreduced.—E. R. The addition of rubber feet reduces thenoise of a rotary-gap to a minimum 140 Popular Scie7we Mo7\thly


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Keywords: ., bookcentury1800, bookdecade1870, booksubjectscience, bookyear1872