316 



SCIENCE. 



[Vol. IX . No. 217 



tailed work.' In addition, the list contains analy- 

 ses of more than 800 springs, and, wherever pos- 

 sible, the temperature, volume, and character of 

 each spring are given. Only those who have done 

 similar work can appreciate the amount of thank- 

 less drudgery involved in this useful paper. 



LETTERS TO THE EDITOR. 



*^*The attention of scientific men is called to the advantages 

 of the correspondence columns of Science /or placing promjMy 

 -on record brief preliminary notices of their investigations. 

 Twenty copies of the number containing his comm,unieation 

 ■will he furnished free to any correspondent on request. 



The editor will be glad to publish any queries consonant ivith 

 the character of the journal. 



Correspondents are requested to be as brief as possible. The 

 ■■W7'iter^s name is in all cases required as proof of good faith. 



Barometer exposure. 



About noon of Feb. 18 the barometer at Blue Hill 

 observatory began to fall rapidly, and continued to 

 do so until about 9 p.m. During this fall the wind 

 steadily increased in velocity, and between 8 and 9 

 P.M. was blowing almost a hurricane. Immediately 

 after 9 p.m. the hurricane-like roar of the wind sud- 

 denly ceased. Glancing up at the observatory baro- 

 graph, I saw that it was raj^idly rising, and within 

 two or three minutes had risen more than a tenth of 

 an inch. The barograph is of the Draper pattern, 

 ^nd multiplies three times. The accompanying dia- 

 gram is a copy of the part of the barograph trace on 

 Feb. 18, showing the rapid rise in pressure referred 



29.0 



38. 9E 





to. There was thunder and lightning for about an 

 hour preceding and following this sudden rise. 



The following are the wind-velocities in miles per 

 hour for each five minutes as obi ained from a Hahl 

 ■anemograph : — 



Time (P.M.) 8.30 8..35 8.40 8.45 8.50 8.55 



Velocities (miles) 65 60 64 69 71 69 



After 9.50 the velocity varied but little for several 

 hours. It is seen that between 9 and 9.05 p.m. there 

 was a sudden decrease in the wind-velocity of about 

 35 miles, coinciding with the sudden rise in pressui-e ; 

 and, furthermore, each of the less-marked fluctua- 

 tions of the barograph curve following this is con- 

 nected inversely with corresponding variations in 

 the wind's velocity. 



The change in wind- velocity was evidently con- 

 nected with the rise of the barograph at 9 p.m.; and 

 the question presents itself. Was the rise of the l3aro- 

 graph evidence of an actual existing difference of 

 pressure in the atmosjihere, or was it a merely me- 

 vchanical effect of the wind sucking the air out of 



buildings while the wind- velocity was high, and 

 allowing it to flow in again as the wind-velocity 

 decreased ? 



From what we know of the connection of wind- 

 velocities with barometric gradients, it would be 

 anticipated that such a difference of pressure in the 

 atmosphere as would cause a rise of the barometer at 

 any point to the extent of a tenth of an iach in a 

 minute or two, would give rise to an enormous in- 

 crease in wind-velocity. But, instead of finding the 

 increased wind-velocity with the rise of pressure, 

 there was just the opposite : hence the inference is, 

 that the rise of the barograph was due to the de- 

 creased wind- velocity relieving the stress on the air 

 in the building. 



On examining the barograph trace obtained by 

 Professor Davis at the Harvard laboratory, ten miles 

 north of Blue Hill, it is found that an almost identi- 

 cal and equal jump of the barograph curve occurred 

 within a few minutes of the rise at Blue Hill ; so 

 that, whatever the origin of the rise, it was evidently 

 due to some general cause acting similarly over a 

 comparatively large area. 



The observations of the signal service taken all 

 over the United States at 10 p.m. show that there 

 existed at that time a large cyclonic storm central- 

 north of Lake Superior. The circulation of the wind, 

 as well as the bending of the isobars, also give un- 

 doubted evidence of the existence, at the same time, of 

 a small secondary over New England. 



An explanation of the sudden decrease of wind- 

 velocity hence suggests itself. Previous to 9 p.m. 

 the vicinity of Boston was on the outer edge of the 

 secondary, where the isobars were greatly crowded 

 and the wind-velocity high ; but at 9 p.m. it suddenly 

 entered the progressing central area of the secondary, 

 where the pressure was more uniform, and the wind- 

 velocity immediately decreased. This explanation 

 necessarily involves the assumption that the pressure 

 in the vicinity of Boston was lower after 9 p.m. than 

 j)receding it, and the apparent rise was merely a sub- 

 jective effect due to the wind. No other assumption 

 seems to me reasonable, especially when we find at 

 10 p.m. the wind over a small area circulating around 

 and centring in toward southern New England. 



H. Helm Clayton. 

 Blue Hill meteor, oliserv., March 25. 



On certain electrical phenomena. 



I hasten to acknowledge that I unintentionally 

 misrepresented Dr. Shufeldt in one sentence of my 



9.00 9.05 9.10 9.15 9.20 9.25 9.30 9.35 9.40 9.45 9.50 

 65 31 36 48 35 15 18 30 37 36 33 



letter in Science, No. 213. I was wrong in afl&rming 

 that he stated that he had never observed such ex- 

 hibitions in Washington ; for what he really said 

 was, that he had never observed them as far as his 

 own person was concerned. 



I hope Dr. Shufeldt will be equally ready to admit 

 that he has misrepresented me in his reply to my re- 

 marks (Science, No. 216), where he has omitted the 

 essential part of one of my sentences, and altered the 

 remaining part, even going so far as to include the 

 ' mangled remains ' in quotation-marks. Any one 

 who will take the trouble to examine my first letter 

 will see that what I really advised him to do was to 

 critically examine his facts, " possibly eliminating a 



