March 24, 1887] 



NA TURE 



491 



of a size sufficiently great to be visible under the micro- 

 scope. But in many other instances I have failed to 

 detect any such indication, even with much higher 

 powers The sm:ill ramifying tubules might at first 

 sight be taken for some traces of a vegetable tissue, but 

 my colleague Dr. Scott assures me th>at they do not in the 

 least resemble any tissue found in the bamboD. I have 

 myself no doubt that it is an inorganic structure. It is 

 not improbably analogous to the peculiar ramifying 

 tubules formed in a solution of water-glass when a crystal 

 of copper sulphate is suspended in it, as shown by Dr. 

 Heaton (Proc. Urit. Assoc, 1S69, p. 127). Similar forms 

 also occur on a larger scale in some agates, and the 

 artificial cells of Traube may probably be regarded as 

 analogous phenomena. 



The aggregates of globular bodies seen in the section 

 so greatly resemble the globulites of slags and natural 

 glasses, and in their arrangement so forcibly recall the 

 structures seen in the well-known pitchstone of Corriegills 

 in Arran, that one is templed to regard them as indicating 

 the beginnings of the development of crystalline structure 

 in the tabasheer. But I have good grounds for believing 

 the structure to have a totally different origin. They 

 seem in fact to be the portions of the mass which the 

 fluid Canada balsam has not succeeded in penetrating. 

 By heating they may be made to grow outwards, and as 

 more balsam is imbibed they gradually diminish, and 

 finally disappear. 



I must postpone till a future occasion a discussion of 

 all the structures of this remarkable substance and of the 

 resemblances and differences which they present to the 

 mineral opals on the one hand, and to those of the opals 

 of animal origin found in sponge spicules, radiolarians, 

 and the rocks formed from them, some of which have 

 recently been admirably investigated by Dr. G. J. Hinde 

 (Phil. Trans., 1885, pp. 425-33). 



I cannot, however, but think that it would be of the 

 greatest service to botanists, physicists, and mineralogists 

 alike, if some resident in India would resume the investi- 

 gations so admirably commenced by Dr. Patrick Russell 

 nearly a century ago ; and it is in the hope of inducing 

 someone to undertake this task that I have put together 

 these notes. There are certain problems with regard to 

 the mode of occurrence of this singular substance which 

 could only be solved by an investigator in the country 

 where it is found. 



Most parcels of the commercial tabasheer appear to 

 contain different varieties, from the white, opaque, chalk- 

 like forms, through the translucent kinds to those that are 

 perfectly transparent. It would be of much interest if 

 the exact relation and modes of origin of the.se different 

 varieties could be traced. It would also be important to 

 determine if Brewster was right in his conclusion that the 

 particular internodes of a bamboo which contain tabasheer 

 always have their inner lining tissue rent or injured. The 

 repetition of Dr. Russell's experiment of drawing off the 

 liquids from the joints of bamboos and allowing them to 

 evaporate is also greatly to be desired. My colleague 

 Prof. Riicker, F.R.S.,has kindly undertaken tore-examine 

 the results arrived at by Brewster in the light of more 

 recent physical investigations, and I doubt not that some 

 of the curious problems suggested by this very remarkable 

 substance may ere long find a solution. 



John VV. Judd 



EXHIBITION OF MARINE METEOROLOGICAL 



INSTRUMENTS 

 'X'HE eighth Annual Exhibition of the Royal Meteoro- 

 •^ logical Society was held in the Library of the Insti- 

 tution of Civil Engineers, 25 Great George Street, West- 

 minster, from Tuesday, March 15th, to Friday, the iSth. 

 The exhibition was specially devoted to marine meteoro- 



logical instruments and apparatus, and such new in- 

 struments as have been invented and first constructed 

 during the past twelve months. 



A very interesting and valuable collection of instru- 

 ments from the Challenger Commission, the Scottish 

 Marine Station at Granton, the Scottish Meteorological 

 Society, and Mr. J. Y. Buchanan, were brought from 

 Edinburgh under the charge of Dr. H. R. Mill, who 

 showed several in action. This set included various forms 

 of deep-sea thermometers, from the early pattern of the 

 Millcr-Casella to the Scottish frame for Negretti and 

 Zambra's reversing thermometer, which has been adapted 

 from Magnaghi's by Dr. Mill. Two specimens of the 

 Miller-Casclla thermometer, after four months' immersion 

 in brackish water, were shown, with the following results : 

 in No. I, which was placed at the surface, the copper 

 case was clean, but the scale figures were entirely 

 obliterated from the porcelain ; in No. 2, which 

 was suspended in 9 fathoms, and at i foot above the 

 bottom, the copper was entirely covered with a green 

 crust, but the scale figures were not rendered illegible. 

 \'arious forms of piezometers for ascertaining the depth 

 when the temperature is known, or the temperature when 

 the depth is known, were also exhibited. These were 

 nearly all constructed by Mr. Buchanan on board the 

 Challenger. Water-bottles for obtaining samples of water 

 at the bottom, or any required depth below the surface, 

 were suspended from the gallery to show their action when 

 in use. The most interesting were Buchanan's sounding- 

 rod and water-bottle for great depths, and Mill's self- 

 locking slip water-bottle for moderate depths. 



The Meteorological Council contributed sets of instru- 

 ments as supplied to merchant ships and the Royal navy ; 

 the Royal Meteorological Institute of the Netherlands 

 e.xhibited a set as supplied to the Dutch navy ; and the 

 Deutsche Seewarte sent a set as issued to the German 

 navy. 



The Rev. C. J. Steward exhibited a set of instruments 

 as used at the Lochbuie Marine Institute, Isle of Mull, 

 which, among others, included a dimenuion thermometer 

 in a box for river temperatures, the box being suitable for 

 the bottoms of pools, or rough stony bottoms ; and a large 

 disk for ascertaining the transparency of the sea. 



In connexion with the deep-sea thermometers Mr. 

 Caselia showed some apparatus originally employed in 

 testing these instruments for the .Admiralty and the Royal 

 Society, and damaged during the experiments; viz., a bottle 

 broken at a pressure corresponding to 2\ miles of sea-water, 

 a steel bar bent at 3 miles, and an iron plug broken at 4 

 miles. Specimens of almost every pattern of deep-sea 

 thermometer were exhibited, including Johnson's register- 

 ing metallic, the records of which are obtained by the 

 varying expansion of brass and steel bars acting upon 

 indices ; Miller-Caselia maximum and minimum ; and 

 Negretti and Zambra's turnover thermometer. 



The barometers exhibited included patterns used in the 

 British, Dutch, French, and German navies. The English 

 marine barometer has an iron cistern and contracted 

 scale, and the gun barometer is mounted with india-rubber 

 packing to prevent breakage caused by gun-firing. MM. 

 Richard Freres, of Paris, sent one of their self-recording 

 aneroids, for use on board ship ; and Mr. Abercromby 

 showed several curves taken at sea by one of these instru- 

 ments in various parts of the world. 



The anemometers shown were : Sir Snow Harris's, 

 which is an improved form of Lind's ; Hagemann's, 

 Robinson's, Black's pressure, and Whipple's maximum 

 pressure, the latter being quite a new instrument. Dr. 

 Black exhibited his marine rain-gauge and evaporator. 

 Among the miscellaneous instruments were various 

 forms of patent logs, current meters, clinometers, and a 

 model of a section of a vessel fitted with lightning 

 conductor. 



In addition to the instruments, a number of charts 



