Public works . PLAN Se.—nxflL ELfVflTI ? APPLIANCE FOR DETECTING MINUTE SUSPENDED MATTER the eye near enough to the sHght suspended particlesto be within ordinary reading distance 12 to 18 , the light illuminated the bottom of theparticles instead of the tops which were visible. The illumination of dust particles in a dark roomby a ray of sunlight suggested the passing of a rayof light through the water approximately at rightangles to the line of sight of the observer, and pro-vision for bringing the eye to within 12 to 18 inchesof the column of water under observation. A number
Public works . PLAN Se.—nxflL ELfVflTI ? APPLIANCE FOR DETECTING MINUTE SUSPENDED MATTER the eye near enough to the sHght suspended particlesto be within ordinary reading distance 12 to 18 , the light illuminated the bottom of theparticles instead of the tops which were visible. The illumination of dust particles in a dark roomby a ray of sunlight suggested the passing of a rayof light through the water approximately at rightangles to the line of sight of the observer, and pro-vision for bringing the eye to within 12 to 18 inchesof the column of water under observation. A number of different ideas were tried out and adevice was finally perfected which is now being usedwith success. In this device a spherical flask filledwith water gives a magnification of approximatelytwo diameters on the side opposite the observer, soif such a flask is used it must be placed where theopposite side is the proper distance from the best condition for the light is at such an anglethat none o
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectmunicip, bookyear1896
