NOVEMBEU 23, 1883.] 



SCIENCE. 



681 



by a crank, and set in motion by a weight of a hun- 

 dred and fifty kilograms placed behind the building. 

 A brake checks the disk. A clock-bell, regulated from 

 within, notifies an assistant either to set in motion or 

 to stop the disk. 



Fig. 3 shows tlie interior arrangement of the cliam- 

 ber. The removal of one of the side-walls discloses 

 the photographic apparatus, A, placed on a bracket, 

 and directed toward the screen. This instrument 

 receives the long and narrow sensitive plates, which 

 just admit the image of the whole screen. The 

 plates which give the best results for the shortest ex- 

 posures are those of Van Monckhowcn of Ghent, 

 and that of Melazzo of Naples. At B is the revolv- 



The low mean temperature is also made a subject of 

 note. 



Georgia. — In this state there has been no general 

 rain since April "23, and the crop reports are in con- 

 sequence unfavorable. Cotton averages sixty-two per 

 cent, and corn seventy-six i)er cent, of the usual 

 yield. The temperatures ranged between 45°, the 

 minimum in the northern portion, and 95°, the maxi- 

 mum in the southern section. The average rainfall 

 was 1.57 inches. 



Indiana. — The temperature averaged 3.5° below 

 the normal for September; and frosts occurred on the 

 Gth, 10th, and 26th, damaging late corn and other 

 vegetation. The prevailing wind was north-east. 



ViG. 2. — Rolling photogr 



ing-disk, which produces the intermittent light; at 

 D, a shutter, which is raised vertically at the begin- 

 ning of the experiment, and falls at the end in order 

 that the light may enter the apparatus only during 

 the time absolutely necessary. £ is a long slit which 

 unmasks before the objective the field in which the 

 movements to be studied are taking place. The dark- 

 ness of the chamber permits one to handle at his 

 ease the sensitive plates, and to change them for each 

 experiment, 



( To be continued.) 



SFA'TEMREll REPORTS OF STATE 

 WEA THER-SER VICES. 



These reports emphasize the general lack of rain, 

 which, without exception, was characteristic of the 

 weather prevailing in every state issuing reports. 



The rainfall ranged from 0.1.") inch to 5.98 inches, 

 averaging 1.09 inches for the state. 



Kansas. — At Lawrence the rainfall was smaller 

 and the leniperatiu-e lower, with one exception, than 

 any other September for sixteen years. Kain fell on 

 seven days, and there was but one thunder-shower. 

 The mean cloudiness was 40..33 per cent^ the month 

 being 0.31 per cent clearer than usual. 



Missouri. — At St. Louis the rainfall was less than 

 a hundredth of an inch, which has not happened 

 before since Dr. Engelmann began his observations 

 in ISJO. The normal rainfall at St. Louis is three 

 inches. Several other stations report no rainfall. 

 Light frosts occurred, but without material damage 

 to the corn-crop, except over limited areas on low 

 ground. 



Ohio. — The barometric conditions were normal; 

 but the temperature was about four degrees below the 



