418 



8CIEJS'CE. 



[Vol. IX., No. 221 



formed. Most of the observations relied upon for 

 proving this effect have been the traces of a baro- 

 graph recording upon Draper's principle, and there 

 have been very few actual observations of a barome- 

 ter. Quite recently there have been observations of 

 a barometer, under varying conditions, on Mount 

 Washington, with wind-velocities of eighty and 

 ninety miles. The results have been published in 

 the Monthly weather review of the signal service, 

 for February, 1887, and are so interesting that a 

 brief review of them is here given. The chimney in 

 the signal office on Mount Washington is about two 

 feet square, and has three inlets into the office- 

 room. One of these is a ventilator near the top of 

 •the room, and the other two have stove-pipes run- 

 :mng from three stoves. It is quite evident that the 

 chimney has a fair communication with the room. 

 The experiments consisted in reading a mercurial and 

 an aneroid barometer, 1", chimney closed ; 2°, chim- 

 ney opened ; 3*^, same as 1" ; 4°, leeward window 

 open ; 5°, same as 1° ; 6°, windward window open ; 

 7", same as 1°. The successive readings were made 

 quite rapidly, though generally three or four min- 

 utes elapsed between each of the seven conditions. 

 Five sets are published with the wind from sixty- 

 five to ninety miles per hour. Under 2° (chimney 

 open), the pressure fell twice mean —.0065 of an 

 inch, and it rose three times mean -I-.0037. Under 

 4° (leeward window open), four times the pressure 

 fell —.019, and once it rose +.002. Under G'* 

 •(win4ward window open), the pressure rose mean 

 .043. Making due allowances for imperfect con- 

 nection between the chimney and the room, it must 

 be admitted, I think, that there is no evidence of a 

 partial vacuum being formed by the suction of 

 winds, up to sixty-five and ninety miles per hour, 

 blowing across the chimney. 



The most interesting results, however, are those 

 with the window open to windward. In an eighty- 

 mile wind, experiment would indicate an increase 

 •of pressure of about .44 of an inch, but here we find 

 the total effect one-tenth of that. It seems to me 

 that the effect of wind on the barometer has been 

 much exaggerated, and we may rest assured that our 

 ■observations during very high winds have not been 

 vitiated so very much. It may be of interest to note 

 that this same slight ' pumping ' or uneasiness of the 

 barometer was noted by Mr. Beall, the observer on 

 Mount Washington in 1883. In making his com- 

 parative readings of the station and extra barometers 

 at the end of each month, he found it necessary to 



exercise the utmost care and speed in order to make 

 correct readings during very high winds. The total 

 oscillation seldom reached .01 of an inch. 



H. Allen. 

 Washington, B.C., April 25. 



The barometer during- thunder-storms. 



My attention has been called to the fact that the 

 time given for the squall of July 21, 1885 (printed 

 ' 1886 ' by mistake in your last issue), did not agree 

 exactly in time with the sharp depression of the 

 barometer shown on the diagram accompanying my 

 letter on p. 392. This was due to an error in the 

 barograph clock, which was then new, and not well 

 adjusted. Mr. Alexander McAdie, who had charge 

 of the station on that day, and Mr. Frank Brown, 

 were watching the barograph during the squall, and 

 both state that the depression of the barograph was 

 coincident with the occurrence of the squall. The 

 squall was so violent that Mr. McAdie wrote that 

 ' life for a while did not seem certain.' 



H. Helm Clayton. 

 Blue Hill meteor, observ., April 23. 



The source of the Mississippi. 

 I am in receipt of a pamj)hlet, entitled ' The 

 source of the Mississippi,' from Ivison, Blakeman, 

 Taylor & Co., and am pleased to see therein that the 

 laurels deservedly won by Nicolett and others are 

 maintained to them. My father, Bazil H. Beaulieu, — 

 who had charge of a trading-post on Lake Itasca in 

 1846 for the American fur company, and who in 1847 

 accompanied, as assistant geologist, the first geologi- 

 cal party (Dr. Norwood, Whittlesey, and others) that 

 went over and drafted Itasca and Elk lakes in going 

 to Ked Lake, and went over the lakes again on 

 their return, and also drafted the Mississippi from 

 its source to Dubuque, lo., — concurs in the opinion, 

 as established by the late survey, that Nicolett was 

 the first man that gave to the world of science a 

 faithful and honest report upon, and maps of, the 

 source of ' Gitche-tebe ' (or ' mighty-water ') Eiver, — 

 the Indian term for the Mississippi. It certainly 

 seems shameful that the vain ambition and venture- 

 some spirit of the Captain Glazier stamp should seek 

 at this late day to aspire to and appropriate to 

 itself laurels nobly won by deserving men in the 

 cause of science half a century ago. 



Theo. H. Beaulieu. 

 White Earth, Minn., March 21. 



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