44 



NATURE 



[September 20, 191 7 



The volume has been used as a text-book in the 

 United States, but we do not think that there is 

 any dang-er of its displacing- British text-books in 

 our own colleg-es. An appendix contains some 

 exercises to be worked by the student, and there 

 are others interpolated in the text and not always 

 easy to find. 



Handbook for Rangers and Woodsmen. By 

 J. L. B. Taylor. Pp. ix + 420. (New York: 

 John Wiley and Sons, Inc. ; London : Chapman 

 and Hall, Ltd., 1917.) Price iis. 6d. net. 

 This is a handbook of pocket size, primarily in- 

 tended as a vade-mecum on all subjects that may 

 turn up in the course of the multifarious activities 

 of the forest ranger or woodsman in the United 

 States. It contains much information that is only 

 indirectly connected with forestry, and will be 

 useful to travellers and settlers g^enerally in the 

 wilder parts of North America.. 



The first part, entitled "Equipment," deals with 

 clothing-, harness, and provisions. The next part 

 is a guide to the construction of telephone lines, 

 paths, roads, bridges, buildings, and fences, and 

 treats, in addition, of blasting, concrete work, 

 painting, and carpentry. The part called 

 "General Field Work " begins with riding, pack 

 animals, and waggons, and concludes with useful 

 notes on felling timber, fighting forest fires, land- 

 surveying, and field cooking. The next part is 

 concerned with the care of horses, cattle, sheep, 

 and swine, and gives an interesting description 

 of the various methods of identification of stock 

 by branding, ear-marks, etc., and of the curious 

 dodges resorted to by cattle-thieves. Another 

 part deals mainly with human ailments and in- 

 juries, reptiles, camp sites, and finding one's way. 

 It is here stated that two species of ant in Arizona 

 and New Mexico throw up mounds, and in nearly 

 every instance leave an opening at the south-east 

 side, presumably in order that the morning sun 

 may warm the runway sooner. 



The appendix contains many useful lists and 

 tables, and concludes with a glossary of peculiar 

 words in use in the Far West. The book is 

 clearly printed on strong thin paper, and is illus- 

 trated with 243 appropriate figures and diagrams. 



LETTERS TO THE EDITOR. 



[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 intended for 

 this or any other part of Nature. No notice is 

 taken of anonymous communications.] 



The Audibility of Distant Gunfire. 



The sound of gunfire from northern France might 

 be expected to be audible in Cambridge, for on the 

 occasion of Queen Victoria's funeral the firing at 

 Portsmouth was clearly heard in this neighbourhood, 

 and even further north, near Peterborough, and the 

 distance from the battlefield is not much greater than 

 that from Portsmouth. But I did not become aware 

 of the sound until one day early in May last, when 

 several volleys of guns were audible about midday. 

 NO. 2499, VOL. 100] 



I The sound was unmistakable for me, as I had heard the 



Queen Victoria funeral guns at a distance of sixty miles 



(in Surrey), and thus recognised the phenomenon at 



once. These particular volleys may have come from 



a little skirmish at sea, or even from gun practice at 



Shoeburyness, for I heard no more for several days. 



; However, they led me to listen carefully, and on the 



I very still nights at the end of May I began to hear 



i the gunfire from the battlefield. It was audible only 



on the south-east side of my house, and there chiefly 



I in a re-entrant angle of the walls. 



I soon found (at the beginning of June) that the 

 ' sound was astonishingly intensified in a garden latrine,, 

 which acted as a resonator like Mr. Carus-VVilson's- 

 garage (Nature, September 6, p. 6), although it is but 

 a tiny building, and differs in being built of brick and 

 having a slate roof. Here the explosions were nearly 

 ! as loud and frequent as I afterwards heard them in 

 { Kent. I compared the intensity of the sounds as 

 I heard at different windows of my house, and found 

 it greatest at the basement, but only on the south-east 

 ' side of the house. I could not detect the sounds in ;j. 

 north-east basement room, so apparently the vibration- 

 did not come through the earth. During June and 

 July the explosions b-icame ever more audible, until 

 I about July 29 they were evident even indoors at mid- 

 day, above the murmur of distant traffic. Since the 

 middle of August they have become less distinct and 

 fewer, and now I can hear either none, or perhaps 

 a few faint booms now and then. The sounds have 

 been heard by other persons in and around Cambridge, 

 j especially in the villages, and I am informed that 

 they have been detected so far north as Downhani 

 Market, in Norfolk. 



In July I spent a few days in Kent, visiting in 

 quick succession Rochester, Maidstone, Ashford, Lydd, 

 Tenterden, and Tunbridge Wells. I was unable tO' 

 detect the sounds at Lydd. They were faint at Ash- 

 ford and Tenterden, clear at Maidstone, more so at 

 Rochester, and especially distinct at Tunbridge Wells» 

 where they were audible through all street traffic. 

 The spot where the sounds were most intense was 

 the rocky combe at Rusthall, where the hollow, 

 bounded by more or less perpendicular escarpinents 

 of rock, acted as a potent resonator. 



It is notable that Lydd is on the plain near the sea, 

 Maidstone, Ashford, and Tenterden on the undulating 

 Weald, and Rochester on a north-west slope of the 

 Downs; also that the Tunbridge Wells valley descend- 

 to the west, and the Rusthall valley to the 

 north-west. Thus in those places where the sounds 

 were most distinct the vibrations had travelled over 

 high ground and arrived in a descending direction. 

 There was no doubt as to the direction whence the 

 sounds came. Wherever the sounds were audible on 

 open ground, in Kent or in Cambridgeshire, one could 

 discern that they came from the south-eastern horizon^ 

 and through the air. F. J. Allen. 



Cambridge, September 15. 



Unusual Rainbows. 



With reference to my letter in Nature of August 30 

 on the subject of "An Unusual Rainbow," and to the 

 replies which were given on September 6, I should 

 like to mention that the sun's altitude and the angle 

 at which the primary bow met the reflected bow were 

 only rough estimations. At the time when the pheno- 

 menon was visible I had unfortunately no instruments 

 at hand. Since then I have calculated the altitude of 

 the sun from a knowledge of the ship's position and 

 the sun's declination and hour angle, and have found 

 it to be about 8° 5'. This gives the angle of inter- 

 section of the bows as 24^° approximately, which is 

 more in agreement with my estimation. The surface 



