6l2 



NATURE 



[October 23, 1890 



bored and killed the tree. Several trees were killed in 

 the same manner. The great peculiarity in these insects 

 is the disparity in size between the females and males, 

 from which it is termed dispar. The female is about 

 the eighth of an inch long, while the male is only about 

 two-thirds of this length. The injury begins by a small 

 hole like a shot-hole being bored in the side of the stem, 

 from which a tunnel is made into the pith, and a branch 

 tunnel running horizontally about half, or two-thirds, 

 round the stem. Other tunnels are made straight up 

 and down. These borings, and the destruction of the 

 pith, soon serve to kill the branch. The only remedy 

 appears to be to cut off and burn the infested limb, and 

 " coating the trees with some wash or mixture, which will 

 not hurt the bark but will prevent the beetle getting in or 

 getting out. One application advised for trial is a thick 

 coat of whitewash with some Paris green in it." 



There is a detailed account of the winter moth, that arch 

 enemy of apple, pear, and plum growers ; this is particu- 

 larly valuable, as it gives the latest experience of practical 

 growers with respect to preventive and remedial measures. 

 The most important of these is the careful banding of the 

 trees in the autumn, before October, with grease and 

 offensive compounds, to prevent the females from climbing 

 up, and the use of arsenites (Paris green and London 

 purple) for washing or syringing infested trees. These 

 washes have been proved to be efficacious in America, 

 where they are universally applied for many insect attacks. 

 In this country, however, cultivators have hesitated to use 

 them on account of their poisonous nature. Miss Ormerod 

 plainly shows that they may be employed without danger 

 and with vast benefit to the fruit grower. For plum trees, 

 the proportion is I ounce of Paris green to lo gallons of 

 water, and for apple trees i ounce to 20 gallons. Testi- 

 mony is given from various growers as to the efficacy of 

 this wash, which from henceforth will, it is presumed, be 

 adopted, as it seems to be the only one which will check 

 the ravages of moths injurious to fruit trees. Full details 

 concerning the use of these American remedies for 

 insect attack are given, which must be most serviceable. 



Want of space prevents allusion to many other insects 

 described in this part of the work. It can only be said 

 that they are clearly and minutely defined, and all that is 

 known of their habits and of means to avert or to 

 modify their mischief is set forth. 



The " Manual " is replete with capital figures of the 

 insects in all stages. Many of these are from drawings 

 executed by Miss Ormerod, and many are the well-known 

 accurate and inimitable designs of Curtis. 



TORNADOES. 

 The Tornado. By H. A. Hazen, Assistant Professor of 

 the United States Signal Office. (New York : Hodges, 

 1890.) 



THIS is a book that will hardly enhance the reputa- 

 tion of its author. Despite his assurance (which 

 of course will not be questioned) that he has endeavoured 

 throughout to be absolutely unprejudiced, its apparent 

 aim is not so much to set before the reader a concise 

 description of tornado phenomena as to controvert the 

 views put forward by Ferrel and others relative to their 

 mechanical and physical constitution, and to substitute 

 NO 1095, VOL. 42] 



for these certain other speculations (we can scarcely call 

 them a theory) which appear to the author to have the 

 merit of greater probability. Prof. Hazen does not, indeed, 

 restrict his condemnation to Ferrel's theory of tornadoes 

 and thunder-storms. As a root-and-branch reformer, he 

 finds himself in opposition to the majority of those who, 

 during the last quarter of a century, have built up the 

 fabric of modern meteorology, for, while he speaks with 

 deference of " the epoch-making experiments of Mayer 

 \sic\ and Joule," he appears to regard as inapplicable to 

 the movements of the atmosphere those laws of thermo- 

 dynamics which are based on the results of Joule's labours. 

 Were it the practice of scientific authors, in imitation of 

 romance-writers, to head their chapters with quotations 

 appropriate to the subject-matter, chapter v. of this trea- 

 tise, more especially, might be fitly introduced with the 

 well-known lines from " Faust" : — 



" Ich bin der Geist, der stets verneint ! 

 Und das mit Recht ! denn alles was entsteht 

 1st werth, dass es zu Grunde geht " ; 



substituting, however, " entstanden " for the present tense 

 of the verb. 



Lest it should be thought that these remarks misrepre- 

 sent or exaggerate the sweeping character of Prof. 

 Hazen's " objections," we extract one or two passages 

 from the chapter in question. On the generally-accepted 

 view that work is performed by an ascending current of 

 air, in pushing aside the atmosphere into which it ex- 

 pands, and that in saturated air the requisite energy is 

 furnished, in part at least, by the condensation of vapour, 

 he observes (p. 52), 



"There is nothing in the science of meteorology, or 

 possibly in any physical science, that has been developed 

 from such a worthless origin as this theory of the libera- 

 tion of energy on the condensation of moisture " ; 



again (p. 54), 



" All the reasoning regarding the diminution of tempera- 

 ture in dry and moist air, as we ascend in the atmosphere, 

 is founded upon purely theoretical considerations. Every 

 experiment, whether in the laboratory or in Nature, has 

 proved that these theories, in their sum and substance, 

 are false " ; 



and again (p. 56), 



" I am inclined to think that even Espy, with all his disad- 

 vantages, was too well informed to adopt such a doubtful 

 and visionary idea as this of effective work performed in 

 the free upper air." 



The familiar lecture experiment illustrative of dynamic 

 cooling, in which a cloud is produced in a receiver con- 

 taining moist air by partially exhausting it with a few 

 strokes of the air-pump, is interpreted in a novel manner 

 consistently with the above opinions (p. 67) : — 



" The presence of haze or cloud is no evidence of saturated 

 air, for such cloud has been produced in air having onl}- 

 2 per cent, of moisture.^ When air is pumped from the 

 room, it has an enormous number of dust particles in 

 it, and these give the appearance of a fog on sudden 

 expansion." 



After these samples of the author's opinions it will be 

 scarcely necessary to notice, in detail, the other numerous 



' Prof. Hazen does not give his authority for this statement, nor does he 

 specify whether the expression is to be understood as 2 per cent, of satura- 

 tion or 2 per cent, by weight or volume. If the former, authentication 

 seems desirable ; if the latter, the fact is obviously irrelevant. 



