344 



NA TURE 



[February 13, 1902 



collision, which seemed almost inevitable, with the roof of the 

 " (Ilastonl)ury Kitchen." Directly after the seizure of the 

 butterfly, Mr. Holland saw the wings fluttering to the ground, 

 evidently cut through at their bases by the beak. — E. B. V. 



I (AN corroborate tne statement that the house-sparrow fre- 

 quently pursues and captures the large white cabbage butterfly. 



I'robably the kestrel preys extensively on the emperor moth, 

 whose wings I have seen lying at the base of the small hum- 

 mocks formed by \.he /uncus squarrostis on the Orkney moor- 

 lands. These tufts were much used as resting places by kestrels 

 and hen harriers, but as neither hawk is capable of catching a 

 bird on the wing, the moths were presumably captured while 

 at rest. 



The black-headed gull feeds on the common ghost moth. 

 ReguLarly every season, during many years, I saw some half 

 dozen or more of these gulls flying backwards and forwards, 

 about three feet above the ground, over the grass in front of my 

 house, hawking after the white oscillating ghost moths in the 

 long summer twilight of a calm Orcadian evening. 



W. Irvine Foriescue. 



7, IJjn Accord Square, Aberdeen, February 3. 



The Severn Bore. 



In Nature of January 23 there is an interesting illustration 

 of the Severn Bore, as photographed by Dr. Vaughan Cornish. 

 If I understand the note rightly, the bore took a little more 

 than a minute to travel 500 yards, and this gives a rate of almost 

 exactly seventeen miles an hour at the given locality. 



On March 13, 1S91, Mr. T. H. Thomas, R.C.A., and I 

 measured the velocity of the bore between a point on the right 

 bank of the river near the King's Head Inn (which is sixty 

 yards north of the sixth milestone from Gloucester on the 

 high road to Newnham) and a point further upon the right bank 

 of the river, near Denny Farm and opposite to the fifth milestone 

 from Gloucester. 



The second hands of two watches were timed exactly together, 

 and we found that the bore reached the first observer at loh. 

 24m. 45s., a.m., and the second at loh. 27m. 4SS., a.m., the 

 interval being 1S3 seconds. 



Measured on the si.\-inch ordnance map, the distance along 

 the central line of the river is 4750 feet. The velocity was 

 therefore 17,"-, miles an hour for the part of the river observed. 

 The river channel there is of a fairly uniform width of 250 feet. 



The date chosen was that of the second highest tide of the 

 spring equinox. At loh. 25m. the height of the bore, above 

 low water level, as measured by a post close to the river bank 

 near the King's Head Inn, was 4ft. loin. As the bore passed 

 on, the level sank to 3ft. 4in. By loh. 30m. the water following 

 the bore reached a height of 5ft. 4in. At loh. 32im the height 

 was 6ft. 4in., and at loh. 34m. the water covered the post, the 

 top of which was nearly 7ft. above low water level. There was 

 thus a rapid rise of the river in the rear of the bore. As seen 

 in midstream, the height of the crest of the bore seemed only 

 about 3ft. above that of the water in front of it. 



There was a gentle breeze from the north-east. Had there 

 been a south-westerly gale blowing up stream, no doubt the 

 phenomenon wou'd have been much more impressive, but it is 

 of interest to record observations made under fairly normal 

 conditions. 



The rushing sound, heralding the advancing wall of water, 

 was audible for some distance. The crest of the bore was 

 whitened by a fringe ol foam, and a good deal of spray was 

 thrown up on the banks, where the water of the wave appeared 

 to be higher than, and somewhat in advance of, that in the 

 middle of the river. 



A small boat in the path of the bore sufiered no inconvenience 

 beyond a slight tossing. The late Frank Buckland greatly 

 exaggerated when he described the bore as " the greatest natural 

 phenomenon in the British Isles," and slated that its pace was 

 equal to that of an express train. Dr. Cornish (Nature, 

 vol. Ixii. p. 127) estimates the velocity of the bore, on April 30, 

 1900, as eight miles an hour between Newnham Ferry and 

 Denny Farm, a river distance of about nine miles. But the 

 velocity evidently increases as the stream narrows, and, in the 

 short portion which we observed, it will be noticed that the 

 velocity was more than twice that estimated over the longer 

 •^'Stance. Chas. T. Wimimkll. 



Leeds, February 3. 



NO. 1685, VOL. 65] 



Persistence of the Direction of Hair in Man. 



In " The Descent of Man," p. 19, under the heading of Rudi- 

 ments, Darwin refers to the long isolated hairs seen in the 

 eyebrows of certain individuals, as representing similai hairs in 

 the superciliary region of the chimpanzee, baboon and certain 

 species of macacus. An analogous phenomenon, with a different 

 significance, found sometimes in the pectoral region in man, 

 seems to be worth notice. I have recently examined two 

 persons, a male aged twenty-eight and a female aged thirty-three 

 years, both with particularly hairless, smooth skin;, and each 

 showing, at a critical point in the pectoral region, certain out 

 standing hairs set closely together, the former three long hairs 

 an inch in length, and the latter two hairs an inch and a half in 

 length. The point of interest lies in the position and direction 

 of these few scattered hairs, which are as noteworthy, in their 

 way, as " erratic blocks " on a level plain. In the female case 

 the two hairs were set just over the middle of the left second 

 costal cartilage, and they pointed persistently iipwanls towards 

 the neck. In the male case the three long hairs were set close 

 to the sternum in the left second intercostal space pointing 

 persistently Jowii-juarJs. The situations of these two curious 

 islets of hair are exactly above, on the one hand, and below, on 

 the other, the level at which the upward chest-stream and the 

 downward chest-stream always divide in a hairy subject. The 

 remarkable persistence in their ancestral direction of these few 

 " fossil " hairs, as they might be called, seems to confirm the 

 view that if man has inherited his hairy covering from a simian 

 ancestry it has been modified in many regions by use and habit 

 since he inherited it. We say that a little straw shows the way 

 in which the wind blows, and I submit that sundry stray hairs 

 on the body of man similarly testify as to the trend of certain 

 mechanical forces which have acted and still act upon him. 



Walter Kuhl 



The Colours of Wings of Butterflies. 



Mr. Croft's letter (Nature, January 2, p. 198) on the 

 subject of colours of wings of butterflies raises an interesting 

 point. 



In pressing the wings of butterflies between sheets of gummed 

 paper in order to obtain impressions for record, I have fre- 

 quently noticed that in those cases where a l>rilliant light blue 

 wing is to be pressed the impression usually fails to give the 

 correct colour ; in transmitted light the impression is not blue, 

 and in reflected light the colour is patchy and of a much darker 

 blue ; for example, the blue of 3.Jiiitoiiia oilhyia. 



I have before me a wing — inside brilliant peacock blue, 

 purple-blue, bronze-brown, according to the incidence of the 

 light ; in transmitted light the colour is brown. The outside 

 of the wing is brown. 



Taking an impression of this wing in transmitted light the 

 impression is brown, in incident light very dark blue and dark 

 bronze in patches ; the peacock blue fails entirely. 



If a scale of this wing be examined under a low power it 

 appears brown in transmitted light, but peacock blue (and varying 

 shades according to position of scale on stage with reference to 

 light) it the transmitted light be cut off and reflected light 

 alone used. 



It would appear, therefore, that this wing owed its chief 

 colours to other causes than pigment. W. G. B. 



India, January 21. 



EXPERIMENTS ON VENTILATING COWLS> 

 'T'HE report of the work of the cosvl committee of the 

 ■'■ Sanitary Institute presents the results of the 

 numerous experiments made by the committee in the 

 course of upwards of twenty years of its existence — an 

 existence unfortunately terminated by the deaths in rapid 

 succession of all its inembers. The last survivor, I\Ir. 

 Rogers Field, 1! A., M.Inst.C.E, the most active member 

 of the Committee, died on March 28, iqoo. 



The committee left in manuscript more or less complete 

 records of some seven thousand experiments on cowls 

 and terminals, together with particulars of the arrange- 

 ments for testing the instruments employed, a synopsis 

 prepared with a view to a comprehensive report, and 



■ The Work of the Cowl Commitlec of the S.anil.-iry Institute. Journal of 

 the Sanitary Institute. (K.d»\\rd Stanford, iQoi.) 



