June 7, 1900] 



NATURE 



127 



we rode easily over a smooth wave. Against the rocky pro- 

 montory which protects the landing-stage the water surged up 

 violently, then subsided 3 or 4 feet, and surged up again 

 more than once. We now put in behind the shelter of this pro- 

 montory. At 7.15 p m. the bore was 300 yards past the ferry, 

 having travelled 3:^ miles, or a little more, in thirty minutes. 

 It was due at the ferry, according to the tide-table, at 7.17 

 p.m. At 7.21 a steady torrent of water was pouring past the 

 promontory. At 7.29 the torrent was roaring, and the standing 

 waves appeared to be 3 feet high. At 7.44 the waves were 



at 8.53 a.m. Taking its time at Newnham Ferry from the tide- 

 table, this gives 70 minutes for time of traversing ()\ miles, or 

 close on 8 miles an hour. The speed below Newnham was one 

 mile per hour less than this. I guessed the height of the bore 

 at 3 feet in the deep water, 4 feet where bursting on the outer 

 bank. The broken water flew higher than this. These, how- 

 ever, are not trustworthy estimates, as I was busy photographing, 

 obtaining seven exposures in all. Fig. i was taken as the bore 

 approached ; in Fig. 2 it is seen in passing, showing the wave- 

 surface at back of the bore itself. When in the boat at Newn- 

 ham I recorded the same thing as a rising and falling of the 

 water against the bank. High water was reached about 9.40 

 a.m. The current continued to flow up stream ; at 10 a.m. it 

 was slack on the concave (western) shore, but still flowing in mid- 

 stream ; at 10.18 a.m. it was distinctly running down even in 

 midstream, the water-level having already fallen nearly 3 

 feet. From the arrival of the bore to the complete turn of the 

 current may be taken to be i^ hours. 



Ordinary photographs show the form of a bore, but its 

 character does not lie so much in its form as in its motion, 

 which combines the mysterious, ghost-like movement of a wave 

 with the rushing steadiness of a railway train. I hope the 

 phenomenon may soon be cinematographed. 



I, Savile Row, W. Vaughan Cornish. 



Fig I. — The Bore approaching. 



smoothed out ; the cui rent appeared to be quite as swift, but 

 the greatly increased depth diminishes the surface effect of the 

 rough bottom. The boatmen tell me that the current was 

 " logged " when a bridge was in contemplation, a velocity of 

 II knots being registered. Owing to dark clouds and a lurid 

 sunset, I took no photographs. After the passing of the bore 

 there was half an hour's gossip at the ferry, with reminiscences 

 of many bores. 



Next morning, April 30, I got into the dog-cart at 7.30 a.m., 

 and drove 6^ miles, much of the way through plum orchards in 



Fig. 2 —Wave .Surface at Back of Bore. 



full blossom, to Denny, 9^ miles by river above Newnham Ferry. 

 Owing to the diff'erence of distance by road and river, it is 

 possible to see the same bore at both places by cycling or 

 driving ; but I required spare time to arrange for photography. 

 The clouds were heavy and a little fine rain fell at times, hence 

 the necessarily instantaneous photographs are not as bright as 

 they should be for successful reproduction. The spot for obser- 

 vation is a cottage garden by the Denny Brook. The river 

 here is little more than 50 yards wide, flowing between sleep 

 banks, slime-covered between tide marks, with no sardy shoals. 

 The bore appeared at 8.47 a.m., and disappeared round a bend 



NO. 1597. VOL. 62] 



Bamboo Manna. 



The recent occurrence of a sweet secretion on the stems of 

 bamboos growing in the Central Provinces is a most interesting 

 fact to students of antiquarian medicine. Bamboo manna de- 

 rives its name from the Sanskrit words — Tvak-kshira, " bark 

 milk " ; Vansa-sarkara, " bamboo sugar" ; and Vansa-karpura, 

 " bamboo camphor." Vansa-lochana is the name by which it 

 is known by Indian physicians at the present day. These terms 

 would signify a manna-like substance exuding from the stem of 

 the tree, but what is known and used as Vansa-lochana all over 

 India is quite a different article. 



That bamboo manna is not a sugar, but a white, gritty body, 

 now called Tabashir by Europeans, is gathered from the account 

 of Dioscorides, and from the fact that no kind of sugar prepared 

 from the sugar cane answering to this description was known 

 in India in his time. Dioscorides writes : " What is called 

 a6.Kxo-pov is a kind of concrete honey, found in reeds in India 

 and Arabia Felix, in consistence like salt, and brittle between 

 the teeth like salt." Tabashir, or bamboo manna, was known 

 to the early Arab travellers in the East, and the port of Thana, 

 on the wes:ern coast of India, was famous for this product in 

 the twelfth century. Tabashir is employed as a medicine for 

 its cooling, tonic, aphrodisiac and pectoral properties. In its 

 crude state, when taken from the inside of the bamboo stems, 

 it is mixed with insect remains, and has a blackish appearance ; 

 but on gently calcining it becomes quite white, with a pearly 

 lustre. It consists of about 80 per cent, of pure silica, with 

 variable proportions of alkalis, water and organic matter. The 

 history and properties of tabashir have been very fully dis- 

 cussed by Sir David Brewster (Phtlos. Trans. 1819 ; Edin. 

 Journ. Science, vol. viii. p. 286) ; Sir George Birdwood 

 {Bombay Products^ pp. 95-96) ; Dr. F. A. Fliickiger {Zeit. 

 des AUg. Osterr. Apoth. Vcr. 1887, No. 14), and by Sir D. 

 Brandis {Indian Forester, March 1887). 



The only modern work which alludes to a sugar in the bam- 

 boo is the " System of Botany," by La Maout and Decaisne. 

 The authors remark : — "The young shoots of these two trees 

 {Bainhusa arundinacea and B. verticelkUa) contain a sugary 

 pith which the Indians seek eagerly ; when they have acquired 

 more solidity, a liquid flows spontaneously from their nodes, 

 and is converted Dy the action of the sun into drops of true 

 sugar. The internodes of the stem often contain silicious con- 

 cretions, of an opaline nature, named tabashir." Here a dis- 

 tinction is made between the manna forming on the outside of 

 the stem and the tabashir found inside, but no reference is made 

 to any record where the first named exudation was observed or 

 examined. Dr Watt, when writing the article on Bambusa for 

 his "Dictionary of Economic Products of India," sums up the 

 general experience with regard to this point, and says : *' nor 

 has the spontaneous excretion of sugar on the outside of the 

 stem ever been recorded by Indian travellers." 



The strange appearance of manna on the stems of the bamboo 

 was reported last March by the Divisional Forest Officer, 

 Chanda, Central Provinces, and notices of this phenomenon 



