‘ & 
146 Miscellaneous Observations on ——" 
one of them is seen in the figure. A disk of thin, varnished card, 
four inches in diameter, being placed underneath, and, by means 
of three small pins thrust through it near the edge, separated 
from the plate as far as possible without ceasing to be sustained, 
namely, feur tenths of an inch, on blowing strongly through 
the tube, the colored water rose in the branch a of the glass 
tube four inches above its level in the branch 4, showing the 
air in the tube Tat the place of junction of the leaden tube, 
four inches and a half above the tin plate, to be rarer,by abouta 
hundredth part, than the surrounding atmosphere. Ina similar 
manner, the air in any part of the tube nearer the plate, is found to 
be rarer, and, in any part farther from it, to be denser than the 
surrounding atmosphere. ‘These results can be explained only by 
referring them to a kind of retrograde influence of the primary 
rarefaction. ‘The current in the lower part of the tube, meeting 
with diminished resistance, in consequence of the attenuated state 
of the air between the disks, rushes forward with greater velocity 
than that with which it issues from the mouth ; and this accele- 
ration of velocity, producing a secondary rarefaction, extends the 
limits of the primary inwards, as just. shown, and outwards by 
increasing the momentum of the radiating currents. 
Boston, December 16, 1840. : ; 
¢ 
J . 
Arr. XVII.—Miscellaneous Observations on Insects, §c. ; bY Dr. 
Jonny 'T. Prunmer, of Richmond, Indiana, in letters to the Ed- 
itors, dated Aug. 11, and Dec. 12, 1840. ; 
Wirnovt the advantage of systematical works, in a desultory 
way, I have long been a deeply interested observer of the habits 
and various developments of living insects, and have witnessed 
many curious phenomena pertaining to them. My botanical 1e- 
searches, prosecuted over hill and dale, through wet and dry, 1° 
the last fourteen years, have often brought me into contact with 
those diminutive specimens of creation, the insect tribes, and have 
thus, no doubt, presented some things to my view, which other- 
wise I should not have seen. Last summer I picked a dozen F& 
cently fallen plums from beneath one of my trees, and placed 
them in a glass jar, one half filled with earth, for the purpose 
