July 24, 1884] 



NA TURE 



287 



adoption of a uniform twist of rifling, now slow-burning 

 powder is used. The increasing twist of rifling was very 

 probably effective in saving the gun when quickly-explod- 

 ing powder was employed. But the importance of an 

 increasing twist of rifling decreases as the action of the 

 powder gas is rendered more nearly uniform. If the 

 pressure driving the projectile throughout could be made 

 perfectly uniform, then a uniform twist would exert a con. 

 stant force to produce rotation. 



Mr. Longridge says :— " So long ago as 17th March, 

 i860, the then Secretary of State for War, in his speech 

 on the Army Estimates, said that ' these experiments 

 proved that they had been wrong in using powder of so 

 quick a detonating nature for artillery practice, and espe- 

 cially for rifled cannon, which required a weaker and 

 slower powder than in the other cases" (p. 113). And 

 twenty-four years later, March 20, 18S4, the Secretary to 

 the Admiralty said : " The old breech-loader had been found 

 to be of no more use than a muzzle-loader, and the Govern- 

 ment had adopted a gun twice as long as the old form 

 of breech-loader." It is not very clear what all this means 

 but it is plain that vast sums of money will be required to 

 provide long guns. Twenty years ago it might have been 

 determined what effect every additional foot in length of 

 a gun had in imparting increased initial velocity and 

 increased steadiness to projectiles ; but something more 

 than the " rule of thumb " would be required to accom- 

 plish this. 



England has of late come to acknowledge the value of 

 technical training, and has shown a readiness to take a 

 lesson from Continental nations. Is it not natural to 

 suppose that some training of this kind might be found 

 useful in settling the proportions of our guns, "and in other 

 matters of the same kind? 



We think that Mr. Longridge has made out his case, 

 and that his system deserves a fair trial in comparison 

 with other promising systems. It has already been 

 deemed worthy of a partial trial at Elswick, in France, 

 and America. Experimental guns on different promising 

 systems might in the first case be constructed of small 

 calibre, and adapted to fire the service projectiles. If 

 these proved satisfactory, then proceed to construct larger 

 guns, and finally let that system survive which was found 

 best fitted for its purpose. p g 



OUR BOOK SHELF 



A History of British Birds. By the late Wiiliam Yarrell 

 V P L.S., F.Z S. Fourth Edition. Revised to the end 

 of the second volume by Alfred Newton, MA F R S 

 continued by Howard Saunders, F.L.S , F Z S Parts' 

 XXI.-XXIV., January to July, 1884. (London: Van 

 Voorst.) • 



Although, as we have said in a former notice of this 

 work, it was a great pity that Prof. Newton could not be 

 induced to complete his revised edition of Yarrell's well- 

 known History of British Birds,"-a subject in which he 

 is before all other living naturalists at home, there can be 

 no doubt that the task has fallen into good hands. Mr 

 Howard Saunders has not only completed a volume in 

 about the same space of time that the former editor took 

 to issue a single number, but has performed his work in 

 a style to which, we think, little exception will be taken 

 The aim of Yarrell's " History of British Birds," we suV 

 pose, is to be sufficiently popular to be understood by all 



well-educated people, and at the same time to be tho- 

 roughly correct in scientific matters, so far as they are 

 involved. As to Mr. Saunders' numerous remarks upon 

 points of synonymy and distribution being entirely free 

 from error, we should be very sorry to guarantee any- 

 thing of the sort. But as we turn over the pages of his 

 recent numbers, very few exceptional statements seem to 

 present themselves, and most of these relate to what are 

 to a certain extent matters of opinion. 



Having finished his Limicolcz in Part XXL, Mr. 

 Howard Saunders naturally proceeds to the Gavia;, a part 

 of his subject with which he is, as we all know, very 

 familiar. An author who has worked out the Larida; of 

 the whole world in a thoroughly conscientious manner, 

 and made this group his special study, is above all others 

 qualified to prepare a special account of the " British " 

 species. Of these Mr. Saunders recognises thirtv as ad- 

 missible into the list, though it is more than probable that 

 this already large number will be still increased bv the 

 arrival in future years of stray individuals belonging to 

 other species of this essentially wandering tribe of birds. 



Congratulating our author on the accomplishment of 

 the first volume of his portion of this excellent work, we 

 may venture to express a hope that he will bring the long- 

 delayed fourth edition of " Yarrell's Birds " to a speedy 

 and satisfactory conclusion. 



Bulletin of the United States National Museum. No. 



19. "Nomenclator Zoologicus." By Samuel H. 



Scudder. Svo. (Washington, 1S82-1884.) 

 Mr. SCUDDER'S "Nomenclator Zoologicus," which has 

 been issued as No. 19 of the Bulletins of the United 

 States National Museum, is not of a generally attractive 

 nature, but will be of great use to working zoologists. It 

 consists of two parts : the first of these, or " Supplemental 

 List," contains the names of genera in zoology established 

 previous to 1884, which are either not recorded or erro- 

 neously given in the previously issued Nomenclators of 

 Agassiz and Marschall. To each generic name is added a 

 reference to the work in which it is to be found. The 

 second portion of Mr. Scudder's volume, or " Universal 

 Index," contains an alphabetical index of all the names 

 included in the "Supplemental List," together with those 

 given in the Nomenclators of Agassiz and Marschall, and 

 in the Indices of the Zoological Records. This second, 

 most important part, contains about 80,000 entries, and, 

 if correctly drawn up, as we have no reason to doubt is 

 the case, will enable a naturalist who has recourse to it to 

 determine at a glance whether any particular name has 

 been already employed in zoology or not. All working 

 naturalists will at once acknowledge the value of such an 

 index as this, and will join us in thanking Mr. Scudder for 

 having produced it. Could Mr. Scudder's index be mag- 

 nified into a " Lexicon Zoologicum," giving the references 

 to all the 80,000 terms in a single volume, a still more meri- 

 torious and useful work would be the result. Until this 

 shall have been accomplished, it will still be necessary for a 

 naturalist to refer to half a dozen or more different works 

 in order to ascertain where any particular generic term 

 has been employed in zoology. 



LETTERS TO THE EDITOR 

 I The Editor does not hold himself responsible for opinions expressed 

 by his correspondents. Neither can he undertake to return, 

 or to correspond with the writers of, rejected manuscripts. 

 No notice is taken of anonymous communications. 

 [The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible otherwise to insure the appearance even 

 of communications containing interesting and novtl facts.] 



Krakatao 



I forward a letter recently received from a former pupil, Dr. 

 Stanley M. Kendall, which gives so graphic a description of the 



