PROGRESS OF METEOROLOGY IN 1889. 241 



piirt with nearly the whole of their vapor iu the act of ascend iug and 

 so do not carry away to other regions the water evaporated from the 

 snrface; the same water is evai>orated and precipitated again and 

 again, and the only loss of water to be supplied by outside winds is 

 that carried off by river drainage, probably less than half of the rain fail. 

 "As the result of a long study of the raiu-fall of India, I have become 

 convinced that dynamic cooling, if not the sole cause of rain, is at all 

 events the only cause of any importance, and that all tlie other causes 

 so frequently appeahnl to, such as the intermingling of warm and cold 

 air, contact with cold mountain slopes, etc., are either inoperative or 

 relatively insignificaut." {Nature, xxxix, p. 583.) 



Accuracy in measurlny rain-fall — From a long series of rain-fall obser- 

 vations Dr. A. Eiggenbach draws the following important conclusions 

 as to the accuracy attainable : 



(1) The irregularity in the areal distribution of rain-fall is so great 

 that the amounts collected in neighboring gauges, similarly exposed, 

 differ on the average by 0.3""" and in extreme cases by 5'""\ Add to this 

 0.2"'"' for instrumental errors, and it will be seen that an accuracy of 

 O.S'""' is sufhcient in the individual daily readings. 



(2) In counting the days of precipitation the minimum amount of 

 precipitation considered should not be under 0.5"'"'. 



(3) In monthly totals, fractions of a millimeter have no meaning. 



(4) Yearly totals which agree to 0.5''"' are to be treated as identical. 

 {Meteor. Zeitschrift, 1889, vi, p. 15(3.) 



Hailstones, structure of. — Mr. E. E. liobinson gives the accompanying 

 diagram of the cross-section of a hailstone measuring 2.9 centimeters in 

 diameter. The center was circular and consisted of opaque ice, about 

 the size of an ordinary hailstone; this was surrounded by a circle of 

 almost perfectly clear ice, this again by a circle of opaque ice, and this 

 once more was surrounded by almost clear ice, but with tine circular 

 lines in it, and bounded by a frilled outline of opaque ice, which imi- 

 tated in shape the spheroidal state of a drop of 

 water. Outside this again was a thick layer of 

 clear ice of crystalline form. The diagram is drawn 

 natural size, the dark spots representing white 

 opaque ice. Other large stones showed the same 

 construction. Mr. 0. D. Holt, iu examining hail- 

 stones, has detected a metallic taste and also a 

 flavor of ozone. All the stones showed an air- 

 bubble at the center. {Nature, xl, p. 151.) 



Floods in the middle Atlatitic States from May 31 to June 3, 1889. — The 

 following description of uni)recedented rains and floods is collated from 

 articles by Prof. T. Kussell, of the Signal Service, and Prof. Lorin 

 Blodgett, of Philadelphia, in the Monthly Weather Review for May and 

 June : 



IL Mis. 224 IG 



