232 



SCIENCE. 



[N. S. Vol. XV. No. 371. 



the mouths of the rivers and the present lines 

 of water communication. First, a great sea 

 dyke should be built at the north end with 

 many locks, and with sluiceways to allow 

 drainage at low tide; this will require some 

 ten years and cost $16,000,000. Then a tract 

 of 52,000 acres in the N. W. part should be 

 dyked and drained, requiring five years and 

 $5,000,000. Continuing the work, in all about 

 a million and a quarter acres would be re- 

 claimed in thirty-three years' time at a cost of 

 $69,000,000. Experience shows that such lands 

 can be rendered arable in about three years; 

 and it is estimated that they could be rented 

 by the state at $7 per acre per year. The 

 report is a model of thoroughness for its con- 

 sideration of every interest involved. The 

 project now awaits the consideration of the 

 legislative body. 



Charles K. Wead, 



Secretary. 



THE ELISHA MITCHELL SCIENTIFIC SOCIETY. 



The Society held its one hundred and 

 thirty-eighth meeting on Jan. 21 at the Uni- 

 versity of North Carolina. The following 

 papers were read: 



' Recently Discovered Minerals in North Caro- 

 lina ' : J. H. Peatt and Colliee Cobb. 



'Arizona, Its Mineral Wealth': J. H. Pratt. 

 Chas. Baskerville, 



Secretary. 



DISCUSSION AND CORRESPONDENCE. 



THE DAILY BAROMETRIC WAVE. 



In the Monthly Weather Review for Nov., 

 1901, Dr. O. L. Fassig has an interesting arti- 

 cle on 'The Westward Movement of the Daily 

 Barometric Wave.' The article is illustrated 

 by charts showing the lines of equal pressure 

 departure in the western hemisphere for each 

 hour of the day for the month of July. Dr. 

 Fassig's study was suggested by my own paper 

 on the eclipse cyclone and the diurnal cyclones, 

 but he was the first to complete charts of this 

 kind and his charts add much to a knowledge 

 of the behavior of the daily barometric wave 

 and will no doubt aid materially in clearing up 

 the cause of this wave. 



The charts show very clearly that the di- 

 urnal areas of high and low pressure have 

 distinct centers like the cyclones and anticy- 

 clones of the weather map, but unlike the lat- 

 ter move rapidly toward the west instead of 

 toward the east. Moreover, the charts show 

 very strikingly the effect of ocean and conti- 

 nent on the depth and position of the diurnal 

 areas of high and low pressure, and one 

 can scarcely doubt that surface heat and cold 

 play a very important part in their forma- 

 tion. 



Particularly instructive in this connection 

 is the behavior of the early morning minimum 

 of pressure. At 2 a. m., Y5th meridian time, 

 it is chiefly over the two Atlantic oceans, and is 

 central over the North Atlantic, the cold ocean 

 at this time of year when contrasted with the 

 surrounding continents. Between 3 a. m. and 

 6 a.m. this barometric minimum passes over the 

 land areas of North and South America and then 

 the low pressure is found central over the cold 

 southern continent where winter prevails, and 

 the pressure scarcely falls below normal in the 

 warmer northern continent. These facts ap- 

 pear to point very clearly to the dependence of 

 this depression on a relatively low surface 

 temperature, and are in line with the sugges- 

 tions in my papers on the eclipse cyclone and 

 the diurnal cyclones, namely that the morn- 

 ing minimum of pressure is the result of a 

 cold air cyclone. 



The afternoon barometric minimum moves 

 from South America to North America during 

 the afternoon following the place of highest 

 temperature, thus indicating its .dependence on 

 surface heating. 



Mr. Fassig does not state from what source 

 his data are obtained. In drawing my own 

 charts I have found a great scarcity of data 

 from over the Pacific Ocean. The data for 

 South America will be greatly added to when 

 Professor Bailey's observations are published 

 in the Harvard Annals. In constructing my 

 own charts I scaled off the values at his sta- 

 tions from the curves published by him in the 

 American Meteorological Journal, Vol. ^11., 

 p. 331. 



H. H. Clayton. 



