262 NATURE-STUDY REVIEW [6:9-Dec..i9io 



pamphlet to be had from the Department of Agriculture, Wash- 

 ington, D. C. 



Cloudiness. The four simple forms of cloud are called 

 respectively: cirrus — high, thin, feathery, fish-scale, flaky, veil- 

 like; stratus — layers, stratified, or even banked with long hori- 

 zontal edges on the lower side; cumulus — mound-like, flat-based 

 fleeces, thunder-heads, the mountains of cloud-land; nimbus — 

 shedding rain or snow. These terms are combined — cirro-stratus, 

 strato-cumulus, etc. — to describe mixed or transitional forms. 

 In weather-predicting, each kind has its own significance, but 

 this is not the same in all parts of the country. 



The amount, that is the proportion of the visible sky, covered 

 with clouds is approximated and reported in quarters or tenths. 



After the start is well made, cloud study becomes more and 

 more interesting. Do not be too easily discouraged at first. 



Precipitation. Kinds of precipitation are rain, snow, hail, 

 and sleet. The quantity may be reported in adjectives, as "light," 

 "moderate," "heavy," — or in inches if one has a rain gauge. A 

 funnel ten square inches in area at the mouth set in a tube of 

 one square inch in cross section inserted in a piece of ordinary 

 conducting pipe a foot or fifteen inches long closed at the lower 

 end, makes a cheap and serviceable rain gauge. The inch- 

 tube may overflow at the top into the conducting pipe or 

 through a perforation near the top. Snow may be caught in an 

 oblong box and depth in inches measured, or it may be melted and 

 measured in the rain gauge, taking into account the area of the 

 catching vessel. 



Sunshine or Insolation. Once a week is frequent enough 

 to make entries in this subdivision. The hours from sunrise to 

 sunset may be reported from the almanac, but preferably from 

 observation. To measure intensity use an insolator at twelve 

 o'clock noon. To make it, obtain a wooden tile with square or 

 oblong cross-section, or remove the ends from a wooden or paste- 

 board box. Poise it on a horizontal surface in such position that 

 the sun's rays will pass through it parallel to the sides of the box. 

 The ratio of the area of the cross-section of the box to that of the 

 illuminated surface within the sharp-lined shadow cast by the 

 walls of the box is a measure of the intensity of the sunshine as 

 compared with vertical insolation. 



A useful exercise is making a "curve" of intensity with 

 measurements taken at each hour from 9:00 A. M. until 4:00 

 P.M. 



