SCIENCE. 



[Vol. XIV. No. 335 



SCIENCE 



A WESKLY NEWSPAPER OF ALL THE ARTS AND SCIENCES. 



PUBLISHED BY 



N. D. C. HODGES, 



47 Lafayette Place, New York. 



Subscriptions.— United States and Canada $3-50 a yeai. 



Great Britain and Europe 4.50 a year. 



Science Club-rates for the United States and Canada (in one remittance): 

 I subscription r year S 3 . 50 



4 " r year 10.00 



Communications will be welcomed from any quarter. Rejected manuscripts wi 

 returned to the authors only when the requisite amount of postage accompanies 

 manuscript. Whatever is intended for insertion must be authenticated by the n 

 and address of the writer ; not necessarily for publication, but as a guaranty of 1 

 faith. We do not hold ourselves responsible for any view or opmion 

 communications of our correspondents. 



NEW YORK, July 5, iSSg. 



No. 335. 



CONTENTS: 



The Thomson-Houston InOAD in 

 Bangor, Mk i 



The Use of Oil aboard United 

 States Naval Vessels 1 



A HisTOKY of Habitations 



Barr Feyrce 2 



Notable Derelicts in the North 

 Atlantic 4 



Progress OF Engineering 4 



Notes and News 7 



Editor 



in the Atlantic. 



\' Plant-Louse in Ohio. 



:e Photographic; Tele- 



Charity AND Knowledge 



Book-Reviews. 



Economic Value of Electric Light 

 and Power 



Treatise on Trigonometry 



The southward movement of ice on the Grand Banks 

 during June was far more decided than for the same month last 

 year and 1886, though scarcely exceeding that of 1887. The prob- 

 able limit, as forecast on the " Atlantic Pilot Chart " for June, has 

 been well reached in the area lying east of the 50th meridian. 

 Since June 4 there were 16 reports of icebergs south of latitude 

 45°, and between longitudes 50° and 47*°. Of these, 1 1 reports 

 fell south of latitude 44°. The southernmost one, a good-sized 

 berg 40 feet high, in latitude 42° 54' north, longitude 49° 54' west, 

 came near proving very serious to one big liner, who slightly struck 

 one of its submerged spurs on a foggy evening, June 11. A few 

 bergs are still coming down across the parallel of 50°, but the sea- 

 son on the southern half of the Grand Banks is drawing to a close, 

 and the probable limit for July has accordingly been moved north- 

 ward. The fact that the fog belt is so apt to overlap the iceberg 

 region at this season makes it doubly desirable that transatlantic 

 lines, both east and west bound, adopt a set of routes that will 

 skirt rather than cross this dangerous field. Such routes are ad- 

 vocated on the " Pilot Chart," and the slight loss of time incurred 

 by following them gives a factor of safety that must in time be 

 recognized by underwriters. It is to be hoped that the coming in- 

 ternational marine conference will give this question their wise 

 consideration. 



THE GRAIN PLANT-LOUSE IN OHIO. 



One of the most notable insect-outbreaks that has occurred in 

 Ohio for many years is now taking place in the grain-fields of that 

 State. The insect is one which has long been known as the grain 

 plant-louse {Siphonophora g7'anaria), having originally occurred 

 in Europe, whence it was probably introduced into this country early 

 in its history. It has only occasionally ravaged grain-fields here, 

 and, so far as our present information goes, has seldom been inju- 

 rious in Ohio. 



The insect is now present, however, in destructive numbers over 

 a large portion of Ohio, having already seriously injured the wheat, 

 and is now threatening an equally serious injury to oats and other 

 grains. Last year it was present in many of the northern counties, 

 not becoming sufficiently abundant to attract notice until the oats 

 were nearly ripe. 



This insect is closely related to the " green fly " of house-plants, 

 rose-bushes, etc. It is a small, greenish, or in some cases brown- 

 ish, insect, with or without wings, infesting the leaves and heads 

 of plants of the grass family. It obtains its food by inserting a 

 pointed beak into the leaf or stem, and sucking out the sap. As 

 the wheat gets ripe, it migrates to the more succulent oats, and, 

 when these ripen, will go to various grasses. It brings forth living 

 young ; and its rate of multiplication is very great, it being esti- 

 mated that a single louse in spring may become the ancestor of 

 many millions before autumn. 



Fortunately this insect has a great many enemies which prey 

 upon it, and are now doing immense good in decimating its ranks. 

 These are of various kinds, and in some places are being mistaken 

 for foes instead of friends of the farmer. The onewhich is causing 

 the most apprehension is a peculiar dark-colored, six-footed insect, 

 generally with spots of a brighter color on its back, looking, as one 

 person expressed it, " half worm and half bug," which is very 

 abundant in the infested wheat fields, crawling about over the 

 heads. These are the young or larvas of various species of lady- 

 bugs, or lady-beetles, and instead of attacking the wheat, as many 

 farmers believe, is really feeding upon the lice themselves, and de^ 

 stroying them by thousands. Another insect that is doing im- 

 mense good is a very small four-winged fly that deposits an egg 

 within the louse. This egg hatches into a grub that develops at 

 the expense of the louse, destroying it, and emerging again as a 

 four-winged fly. The dead lice " struck " by these parasites be- 

 come dull brown in color, and adhere to the leaf or stem upon 

 which they were feeding. 



Besides these, various other enemies are attacking the lice ; and 

 the indications now are that the outbreak will be so checked by 

 the end of the season, that there will be little danger of a repetition 

 of the attack next year. 



The presence of English sparrows in the wheat-fields led some 

 to believe that they were feeding upon the lice ; but an examination 

 of stomach contents of a number shot while on wheat, showed that 

 the grain itself was what they were after, no more lice being eaten, 

 than. was necessary to get the grain. 



As yet no practical artificial remedy for the grain plant-louse is 

 known. At the Ohio Agricultural Experiment Station at Colum- 

 bus they have found that kerosene emulsion will destroy them ; but 

 the difficulty of reaching them with this substance, when they occur 

 on the under surface of the leaf, or embedded in the chaff of the 

 head, makes the remedy hardly practical. The injury to the wheat 

 will be manifested by the shrivelling of the grain, due to the ex- 

 traction of the sap necessary for its perfect development. 



THE BRUCE PHOTOGRAPHIC TELESCOPE. 



The Astronomical Observatory of Harvard College has received' 

 from Miss C. W. Bruce of New York a gift of fifty thousand dol- 

 lars, to be applied " to the construction of a photographic telescope 

 having an objective of about twenty-four inches aperture, with a 

 focal length of about'eleven feet, and of the character described by 

 the director of the observatory in his circular of November last ;. 

 also to secure its use under favorable climatic conditions in such a, 

 way as in his judgment will best advance astronomical science." 



