Report on the etiology and prevention of yellow fever . lution of gelatine, boiling to remove thealcohol, and then pouring the gelatine upon a glass plate, where it isallowed to dry. By means of Canada balsam another glass plate iscemented to the one having the stained gelatine coating to preventthis from being scratched. Some of my photomicrographs have been made by means of thecalcium light, but the greater number have been made by gaslight,which has a decided advantage over any other artificial light known tome ou the score of convenience and economy. I prefer sunlight andthe use of a helio
Report on the etiology and prevention of yellow fever . lution of gelatine, boiling to remove thealcohol, and then pouring the gelatine upon a glass plate, where it isallowed to dry. By means of Canada balsam another glass plate iscemented to the one having the stained gelatine coating to preventthis from being scratched. Some of my photomicrographs have been made by means of thecalcium light, but the greater number have been made by gaslight,which has a decided advantage over any other artificial light known tome ou the score of convenience and economy. I prefer sunlight andthe use of a heliostat, on account of the shorter exposures, but anextended experience has shown me that there are many disappoint-ments when one depends on the light of the sun. On the day we haveselected for making our i)hotomicrographs it may be obscured byclouds, and often for weeks together there will be no day suitable forour purpose. My apparatus for making photomicrographs by gaslight is shownin Fig. 5; a is the camera, which has a pyramidal bellows front, sup-. Ijorted by the heavy block of w;ood b; this can be pushed back uponthe baseboard which supports it, so as to allow the operator to placehis eye at the eyepiece of the microscope. When it is brought forwardan aperture of proper size admits the outer extremity of the eyepieceand shuts out all light except that coming through the objective; c isthe microscope, d the Abbe condenser supported upon a substage; eisa thick asbestus screen for protecting the microscope from the heatgiven off by the battery of gas-burners /. This asbestus screen has anaperture of proper dimensions to admit the light to the condenser d. ETIOLOGY AND PREVENTION OF YELLOW FEVER. Ill The gas burners are arranged in a series witb the i3at portion of theflame facing the aperture in the asbestus screen e. The concavemetallic mirror g is properly phiced to reflect the light in the desireddirection. I have not found any advantage in the use of a condensingle
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Keywords: ., bookcentury1800, bookdecade1890, bookpubl, booksubjectyellowfever
