SCIENCE. 



81 



scatter the rays of shorter wave length, thus leaving the 

 orange-red rays predominant in the emergent light. This 

 view was speedily verified by a ciitical examination of 

 the track of the traversing beam. A sensible turbidity 

 was visible, in the darkened room, at the extremities of 

 the column of water adjacent to the corks securing the 

 glass plates ; and the light diffused latterly at these por- 

 tions, when examined by Nicol's prism, was found to be 

 distinctly polarized. The emergent beam examined by 

 the spectroscope, exhibited orange and red in full inten- 

 sity ; but the yellow and green were greatly diminished. 

 Ten days later (January 2, 1879) the solar beam travers- 

 ing the same column of water emerged much brighter 

 than on Christmas day, and the tint was orange tinged 

 with yellow and red. This long repose caused, doubt- 

 less, some of the resinous precipitate to become more 

 generally diffused, or to subside, and thus diminished the 

 turpidity of the liquid. The recognition of the dichroism 

 imparted to water by the presence of finely-divided par- 

 ticles in suspension, serves, likewise, to harmonize the 

 conflicting views promulgated by physicists who have 

 studied the chromatic phenomena presented by this 

 liquid. Some claim that the rays of higher refrangibihty 

 are more copiously withdrawn by absorption ; while others 

 maintain that the rays of longer wave lengths are more 

 absorbed. In many cases the chromatic tints ascribed to 

 selective molecular absorption are unquestionably due to 

 selective diffuse reflection from the ultra-microscopical 

 corpuscles which are held in suspension. (Vide Jamin's 

 " Cours de Physique," 3d ed., tome 3, p. 447, et seq.) 



ON THE IMPORTANCE OF ENTOMOLOGICAL 

 STUDIES.* 



" Occasionally, at the present day, we may hear insects 

 and entomologists spoken of as 'bugs' and 'bug-hunters' 

 — epithets applied in derision to what are regarded as 

 petty objects and trivial pursuits. Such views only be- 

 tray an ignorance which is equally pi iable and inexcus- 

 able. The study of insects has assumed an importance 

 in its direct application to agriculture, horticulture and 

 sylviculture, second to no other department of natural 

 history. It has called to its aid some of the best intellect 

 of the country. Its literature has become extensive and 

 assumed a high rank. Our State governments, in re- 

 sponse to demands made upon them, are appointing 

 State Entomologists. Our General Government is mak- 

 ing liberal appropriations for entomological work in the 

 Department of Agriculture at Washington, and also for 

 sustaining a special United States Entomological Com- 

 mission, now in the third year of its operations, charged 

 with the investigation of a few of our more injurious in- 

 sects. 



" The study of insects assumes an importance in this 

 country far greater than in any other part of the world. 

 No where else does mother earth yield in such variety 

 and in such abundance her agricultural products ; alter 

 supplying to repletion our own people, the excess is dis- 

 tributed to every quarter of the globe. Few, surpris- 

 ingly few, of these varied products are native to our soil. 

 Nearly all of our fruits, grasses, cereals and vegetables, 

 and perhaps three-fourths of our weeds are of foreign 

 importation — mainly from Europe. With their intro- 

 duction, very many of the insects that preyed upon them 

 were also introduced, or have been subsequently brought 

 hither. But unfortunately for us, the parasites which 

 preyed upon them and kept them under control, have 

 for the most part, been left behind. As the result, the 

 imported pests, in their new home, find their favorite 

 food-plants spread out in luxuriant growth over broad 

 acres, where they may ply their destructive work without 



* From an address before The Farmers' Club, Onondaga Co. N. Y. 



hindrance or molestation, until some native parasites 

 acquire the habit of preying upon them. 



" The grand scale upon which our crops are grown as 

 no where else in the world —demanding for their gather- 

 ing the invention of special mechanical contrivances, and 

 that horse power should be replaced by steam — has also 

 as its attendant inevitable evil, an enormous increase of 

 insect depredations. This may be illustrated by a refer- 

 ence to our apple-tree insects. ******" r n 

 like manner, any and every crop cultivated on a large 

 scale offers strong invitation to insect attack, and won- 

 derfully stimulates insect multiplication." 



Professor J. A. Lintner. 



CLOUD COLORS. 



This P. M., from about 3.30 to sunset, I was witness to 

 a remarkably vivid display of cloud-colors ; and thinking 

 that a full description of the phenomena may perhaps help 

 to the understanding of the conditions of the higher at- 

 mosphere, I have written out what I saw. The day had been 

 the warmest of the season. The night before was cloudy, 

 and the temperature hardly fell below the freezing point. 

 Light clouds prevailed through the day ; at 3.30 the stand- 

 ard and maximum thermometers stood together at 62°, 

 while the maximum sun thermometer registered 119 . 

 The day had been quite still, the direction of the very light 

 wind being from the S. E. The clouds in the neighborhood 

 of the sun were of two varieties, the lower a fleecy and tufted 

 cloud of the cumulus order, moving pretty rapidly from a 

 little north of west, and frequently exhibiting a rapid spiral 

 movement in the filaments, the other would be called cirro- 

 stratus, though not precisely the typical cloud of that 

 name, as portions were quite free from any appearance of 

 structure. In the less dense portions an arrangement in 

 parallel fibres was, however, quite apparent, — one set nearly 

 horizontal, the other inclined at about 45 , the south end 

 upward. The horizontal arrangement predominated, 

 while the other was visible here and there in a detached 

 streamer and occasionally in striae upon the longer belts, 

 which, hence, were not, as is usual with this cloud, striated 

 perpendicularly to the direction of the bands. These 

 cirro-stratus clouds, which also moved from the west, 

 though with a much less velocity than the lower ones, 

 were the only clouds which showed the rainbow colors. 

 These were exceedingly intense, and changing every mo- 

 ment with such rapidity as to make it very difficult to de- 

 cide upon the order of the colors, the more so as every 

 filament had its own rainbow, and all were shifting. The 

 red was, however, generally nearest the sun, though some- 

 times bordered inwardly with intense yellow. The most 

 perfect succession of colors which I caught was in a cloud 

 extending horizontally northward from the sun, in which 

 for a brief interval all the seven colors could be traced fol- 

 lowing one another, not in the direction of the sun, but 

 vertically, the red uppermost. The violet was, however, 

 so very brilliant as to suggest the beginning of a new- 

 rainbow at its bottom, and in a moment this cloud had 



adopted the form which was most common throughout, 



bands of red above and below, with a broader band be- 

 tween of yellow or green or blue. This blue tint was often 

 exceedingly brilliant, tipping both ends of filaments, which 

 were of dull hue in the centre, and bordered above and 

 below with parallel stripes of red. A purple shade was 

 occasionally distinct, surrounded by other colors. This 

 undescribably beautiful display continued over the whole 

 S. W. quarter of the sky, until the sun had been out of 

 sight behind the mountains for more than half an hour. 



Though the clouds upon which the colors were observed 

 were of the order in which halos are formed, yet the ap- 

 pearance had very little in common with the halo, — of 

 which we have had a good example within a week. The 

 colors were not only not concentric, but were exhibited 

 successively by different clouds in every direction from the 

 sun, and at all distances, from 30°, or. perhaps. 40°, to 



