December 5, 1902.] 



SCIENCE. 



909 



and consequent higher temperature, can be 

 given to the gas which has passed into the 

 second receiver by the portions vchich subse- 

 quently enter it. This is due to the fact that 

 he ignores the motion of translation which 

 the entering gas possesses. A mass of gas in 

 motion as a whole, will act on another mass 

 of gas in the same way as a moving piston, 

 namely, increase the velocity of the molecules 

 which collide with it. 



Detailed criticism of Mr. Fireman's paper 

 will have to be suspended until its publication. 

 The statements in the abstract are very vague, 

 and the author certainly does not show how 

 the molecules with slow velocities force their 

 way back against the rushing stream, and con- 

 gregate in the first receiver. 



We sometimes find the statement in text- 

 books that a gas expanding under such condi- 

 tions that no work is done experiences no 

 cooling, for example, when expanding into an 

 infinite vacuum. It appears questionable, 

 however, whether a gas can expand without 

 doing work. Leaving out of consideration 

 the internal work, i. e., the overcoming of the 

 forces of cohesion, we still have the gas in 

 the receiver doing work in giving a motion 

 of translation to the mass of gas thrown out 

 into the vacuum. E. W. Wood. 



Johns Hopkins UNivERsrrT. 



BITTER ROT OF APPLES. 



In the article upon this subject in Science 

 for October 24, 1902, page 669, there is no 

 reference to similar investigations with like 

 results previously published. There is, how- 

 ever, an intimation that earlier knowledge 

 was insufficient to justify publication. 



There is sent herewith a ' circular ' and a 

 ' bulletin ' issued by the Agricultural Experi- 

 ment Station of the University of Illinois, 

 which were put into the mails on respectively 

 the fourteenth and twenty-ninth days of July 

 of this year. Of the first there were sent out 

 1,200, and of the second 20,000 copies. They 

 have each been referred to or copied entire 

 in at least one hundred different periodicals 

 throughout the country. Copies were mailed 

 direct on the days indicated to the author 

 whose name is signed first to the article now in 



question, and he may easily have first learned 

 by this means of Mr. Simpson's discovery. 

 At all events the publication of July 14 was 

 in the possession of the general public before 

 those special studies were begun in Illinois 

 by the authors of this later paper. 



Field studies made on July 11, 12 and 13 

 in orchards near Parkersburg, Olney, Clay 

 City, Salem and Tonti, Illinois, by Professor 

 J. C. Blair and myself, left no room for doubt 

 that the early infection of the fruit was 

 mainly from the limb cankers. These cankers 

 were found, after we learned how to look for 

 them, as sources of such infection in hundreds 

 of instances with not five per cent, of fail- 

 ures. Then two hours with the compound 

 microscope on the evening of July 12, at our 

 laboratory at Salem, demonstrated beyond cavil 

 the protrusion of the spores of this specific 

 Gleosporium from the cankers. Such spores 

 positively so produced were at this time in- 

 oculated into fresh apples, and the resultant 

 spots, which showed on the 14th, were clearly 

 identified as those of bitter rot on the 15th — 

 three days after the inoculations — while check 

 punctures remained sterile. These tests were 

 often repeated during following days, with the 

 same results. 



This disease of the apple has annually 

 caused serious losses, amounting to over 

 $1,500,000 in the same region of Illinois two 

 years ago. Here was evidently a new and 

 presumably an efBcient method of combating 

 the scourge if prompt action should be taken. 

 Surely delay in making the facts known 

 would have been reprehensible. As a matter 

 of pure science the subject was sufficiently 

 ripe for publication on the 29th of July as 

 the bulletin fairly shows. T. J. Bderill. 



Unb'eksitt op Illinois. 



a peculiar hailstorm. 

 During the past summer, while on a recon- 

 naissance survey in southern Keewatin, for 

 the Geological Survey of Canada, the writer's 

 party encountered an unusual number of elec- 

 tric storms, particularly during the months 

 of June and July. Quite frequently these 

 storms were accompanied by heavy rain and 

 hail. The heaviest of these commenced about 



