July 8, 1SS7.] 



SCIENCE. 



Brooklyn Entomological Society has appointed a committee to 

 welcome the members of the club, and to assist in making tlie 

 meetings interesting, as well as to give such information regarding 

 matters of special interest to entomologists as may be desired. 

 The same society will arrange for one or more field-excursions 

 in the vicinity of New York, and a reception will be arranged for. 

 Members of the club intending to contribute papers will please 

 communicate the same to the president. Prof. J. H. Comstock, 

 Ithaca, N.Y., or to the secretary, Mr. E. Baynes Reed, London, 

 Ontario. 



— The Botanical Club of the American Association will hold 

 its meetings, as usual, during the week of the association. For 

 particulars address Mrs. E. L. Britton, secretary of the club, 

 Columbia College, New York. 



— The Society for the Promotion of Agricultural Science will 

 hold its eighth annual meeting in New York, beginning on Monday 

 evening, Aug. S, at Columbia College, and continuing on Tuesday. 

 For further information address Prof. W. R. Lazenby, secretary, 

 Ohio State University, Columbus, O. 



— The aggregate production of shad for distribution the present 

 season by the United States Fish Commission has been enormous. 

 The number produced has been increasing from season to season, 

 owing to the perfection of the methods in use. A summary of the 

 distribution for the present season, arranged by river-basins, is as 

 follows : — 



Penobscot River 1,169,000 



Kennebec River '. Soo.ooo 



Tributaries of Narragansett Bay 1,275,000 



Hudson River and tributaries i,97g,ooo 



Tributaries of Delaware Bay 5,099,000 



Tributaries of Chesapeake Bay 68,149,000 



Tributaries of Albemarle Sound 5,322,000 



Tributaries of South Atlantic coast 3,566,000 



Tributaries of Gulf of Mexico 7,048,000 



Inland waters 1,014,000 



Total 95,421,000 



It will thus be seen that over 6S,ooo,ooo young shad-fry have been 

 returned to the waters of Chesapeake Bay. The entire production 

 of the fisheries of the Chesapeake for the present season was about 

 2,000,000 young shad. It is therefore evident, that, for every mature 

 shad taken from the waters of the Chesapeake, thirty-four young, 

 healthy, and vigorous shad have been returned to those waters. 

 Experiments already made by the commission indicate, that, up to 

 the close of their river-life (the young shad migrating in October), 

 twenty per cent of the fry placed in our rivers will survive, and at- 

 tain a size of from two to three inches in length. Arrangements 

 have been made by the commission to secure complete statistics of 

 the shad-catch all along the entire coast for the present year, similar 

 statistics having already been collected in 1885 and 18S6. Informa- 

 tion already in the hands of the commissioner makes it certain that 

 the aggregate production of shad on the coast has been larger the 

 present season than at any time in the last twenty years, but it will 

 be impossible to give the measure of increase. For the Potomac 

 River it is already assured that the increase of 1887 is fully 100,000 

 shad over that of 1886, and the increase of i886 over that of 1885 

 exceeded 100,000. In the Potomac fisheries alone in the last two 

 seasons the increase in shad has been over 250,000 ; the increase 

 representing a much larger number than the entire catch of 1879, 

 in which year the fisheries of the Potomac reached their lowest 

 ebb. 



— Professor Riley, the entomologist of the Department of Agri- 

 culture, has made public the result of an exhaustive personal 

 investigation into the habits of the Phorodon humili, or hop-louse. 

 His discoveries are expected to prove of great value to hop-growers, 

 as he has succeeded in learning the habitation of this plant-pest 

 during the winter months, and tracing it through the varying stages 

 of insect-life. Before the investigation, it was not known how or 

 where the insect survived the winter. As a result of his inquiries. 

 Professor Riley has satisfied himself that the eggs laid by the 

 female at the close of the summer are deposited in plum-trees, 

 where the insect hatches in the spring, and resides until the third 

 generation. This third brood, unlike its predecessors, is winged, and 

 immediately after development abandons the plum-tree and attacks 



the hop-vine. In the autumn a counter-migration from the hop-vine 

 to the plum-tree occurs, the winter eggs are deposited, and the cycle 

 of life goes on in the same way. It is a notable fact that in regions 

 where the cultivation of hop-vines is a new industry, the growers 

 have had complete immunity for a while from the pest. In Cali- 

 fornia to-day they are not troubled by it. Professor Riley believes 

 that the Phorodon humili has been brought to this country from 

 Europe on plum-stock ; and there is reason to believe that the 

 Phylloxera, the dreaded grape-pest, was carried from this country 

 to Europe on grape-vine cuttings. Therefore California hop- 

 growers are warned to beware of importing plum-stock from east- 

 ern hop-regions. These discoveries render it possible to check the 

 ravages of the hop-louse either by the use of insecticides in the 

 springtime, before the insect has reached the winged state, or by 

 the destruction of the sheltering plum-trees. The e.xperiments will 

 be continued with a view to protecting the hop-vines after they 

 have become infected with the hop-louse. 



— The project of holding a summer school of physics at Harvard 

 College this season has been abandoned; but on July 19 and 20 

 apparatus designed for use in the ' forty-experiment course,' prepar- 

 atory for admission to Harvard College, will be shown to teachers 

 or others at the Jefferson Physical Laboratory, and questions re- 

 lating to the experiments will be answered. The same thing will 

 be done for the ' sixty-experiment course ' on the second day, 

 July 20. 



LETTERS TO THE EDITOR. 



%* The atteniio7t of scientific 



ailed to the advantages of the 



columns of ^iZVB.'HQ'^ for placing prontptly on record brief prelitninary notices of 



their investigations. Tivejity copies of the nmnber containing his communication 

 ■will be furnished free to any correspondent on request. 



The editor voill be glad to publish any queries consonant "with the character of 

 the Journal. 



Correspondents are requested to be as brief as possible. The writer's name is 

 in all cases required as proof of good faith. 



Theoretical Meteorology. 



A REVIEW of Professor Ferrel's recent work on this subject in 

 Science for June 3 furnishes an opportunity to present a few points 

 on this subject. Professor Laughton, ex-president of the Royal 

 Meteorological Society, once said that there was hardly a theory 

 in meteorology that was well established. If this be so, it seems 

 to me there is great danger of putting too much reliance upon 

 mere theory, which does not have a sufficient groundwork of 

 facts. There is special danger of this in meteorology, where the 

 mathematical discussions of gaseous movements and vortices are 

 hedged about with so much difficulty and complication. I am 

 well aware that the views here advanced are opposed to those of 

 many most advanced thinkers in this field, and I only ask an un- 

 biassed hearing. 



To my mind there are at least two fundamental errors in this 

 subject, but these are intimately interwoven throughout its warp 

 and woof. These are, first, that there is friction only between the 

 air and the earth, or at least that friction between contiguous air 

 strata may be neglected ; second, that conditions and changes of 

 pressure, temperature, and moisture in the atmosphere, are the only 

 causes acting in producing either its general motions or storms. 



The objections to the first theory are briefly as follows. At a 

 height of 100 feet, or at the most 200 feet, in a level country, there 

 is no longer friction between the air and earth, but rather between 

 air and air. This is especially the case on the ocean ; and here, 

 surely, we would have no waves, if it were not for the friction 

 between air and air. If there were no friction, all storms would 

 take place in a virtual vacuum, and into a vacuum air would tend 

 to flow with about the velocity of sound. Professor Ferrel thinks, 

 that, according to laws of gaseous motion, the earth's atmosphere 

 would leave the poles and heap itself at the equator, but this is pre- 

 vented by friction with the earth's surface ; but, as we have just seen, 

 we need consider only friction of air on air at 100 feet elevation. 



The objections to the second theory cannot be set forth as 

 easily as the above. When we are gravely told that the sun 

 heats up a certain portion of the earth's surface, and that in con- 

 sequence vertical currents are set up which finally bring about a 

 wind of 100 miles an hour, we can but be credulous. As a matter 



