582 



NATURE 



[October 13, 1898 



quantities, and raising it when the proportion is increased. The 

 addition of either potash, soda, lithia, fluorspar, lime, or calcium 

 phosphate raises the coefficient of expansion of a glass, but with 

 the exception of the last, which/may be added up tp 20 per 

 cent., not more than 8 per cent, can be used. For pro- 

 portions higher than this, the glass either refuses to take up any 

 more, or else becomes devitrified and opaque. Calcium borate, 

 oxide of iron, alumina, and silica have the effect of lowering the 

 coefficient of expansion, alumina being especially active in this 

 respect. 



The following neat result in the dynamics of impact is proved 

 by Ingegnere D. De Francesco in Xhe. Rejidicotito oi the Naples 

 Academy for July :— In the impact of two perfectly smooth solid 

 bodies, the kinetic energy due- to the velocities lost is a 

 minimum compatibly with the final value of the difference of 

 normal velocity of the points of contact. It is to be observed 

 that the function which De Francesco proves to be a minimum 

 is not the actual kinetic energy lost by impact, but a quadratic 

 function of the differences of velocities before and after impact of 

 the same form as the kinetic energy.' The theorem is somewhat 

 analogous to several of the " minimum " theorems given in the 

 chapter on "Vis Viva "in Dir. Routh's familiar "Elementary 

 Rigid Dynamics," and, to use- a common way of speaking 

 among mathematicians, the result "comes out in about a 

 line." 



We have received from Major-General Schawacopy of papers 

 read before the Wellington Philosophical Society, on Austra- 

 lasian weather charts and New Zealand storms. Charts were 

 exhibited illustrating types of summer and winter storms, and 

 showing their progress eastward from the Great Australian 

 Bight to New Zealand. The author urges that the phenomena 

 exhibited in these charts of horizontal motion and atmospheric 

 pressure, need for their elucidation a knowledge of the vertical 

 circulation. With this object he has constructed a wind vane 

 showing the wind direction both vertically and horizontally, and 

 has made careful observations during several months. The 

 observations showed that at times the upward or downward 

 inclination prevails for hours, while at other times there may be 

 for hours no regular deviation from the horizontal. The author 

 refers to similar experiments by Prof. A. Klossovski at Odessa, 

 which have been noticed in our colilmns, but makes no mention 

 of those made by the Rev. M. Dechevrens at Zi-ka-wei 

 Observatory. 



The Report of the Meteorological Commission of the Cape 

 of Good Hope for the year 1B97 has been published. Baro- 

 metric and thermometric observations are recorded from forty- 

 six stations, and observations ot rainfall from 336 stations. As 

 an encouragement to continuous observations, the Commission 

 presents to observers the instruments with which they have 

 made a series of satisfactory observations for a period of not 

 less than five years. Among the Contents of the Report, in 

 addition to the meteorological statistics and summaries, are 

 useful notes for the guidance of observers, prepared by Mr. C. 

 M, Stewart, Secretary of the Commission, and a short paper by 

 Mr. A. Struben, upon the rainfall maps of South Africa, 

 prepared by Dr. A. Buchan. The Report is illustrated by a 

 map showing the distribution of summer and winter rainfall in 

 percentages of the mean annual fall over the whole of South 

 Africa, and by diagrams showing the mean monthly rainfall in 

 each division, and the departures from the means of 1885-94. 

 Another report of meteorological observations lately received 

 contains the results of observations made during 1897 in the 

 four Government observatories at Bangalore, Mysore, Hassan, 

 and Chitaldrug, under the direction of Mr. J. Cook. A 

 comparison is made between the results for 1897 and the 

 means of the weather elements at these places during the last 

 five years. 



NO. 151 I, VOL. 58] 



A NOVEL plan has recently been carried out at the Avon- 

 mouth Dock, at Bristol, for increasing the capacity of the lock so 

 as to adapt it for the use of the larger vessels which have for 

 the last few years been coming into use. The length between 

 the gates of the lock, as originally constructed, is sufficient to 

 dock a vessel 425 feet in length ; but the vessels now trading 

 between Bristol and Canada are 465 feet long, and could there- 

 fore only enter and leave the dock at spring tides. To provide 

 for their entering at all tides, the useful length of the dock has 

 been increased by the adoption of a floating steel ca,isson which 

 fits into grooves cut in the masonry of the lock walls beyond 

 the outer gates, and which serves the same purpose as the gates, 

 only giving an increased length to the space available for locking 

 of 40 feet. This caisson is 70 feet long, 30 feet wide, and 

 46 feet high. When the vessel has entered the lock, the caisson 

 is floated from its berth and placed in the grooves ; the tanks 

 are then filled with water sufficiently to sink it on to its sill. 

 When the locking is completed, the water is pumped out, and 

 the caisson floated back to its berth. The steamer Montrose, 

 which arrived from Canada a few days since with a large cargo 

 of provisions, on a neap tide, and which is 465 feet in length, 

 was the first vessel to be docked by the aid of the caisson. 



The Report of Dr. D. Prain, the Director of the Botanical 

 Survey of India, for the year 1897-98, is largely occupied by a 

 continuation of Prof. Woodrow's Flora of Western India. He 

 records the botanical explorations which have been made during 

 the year of portions of Assam and Burma ; in the latter of which 

 great assistance was rendered by Lieut. E. Pottinger, R.A. 



A NEW edition of Mr. C. J. Woodward's "Arithmetical Chem- 

 istry," Part L, has been published by Messrs. Simpkin, Marshall, 

 Hamilton, Kent, and Co., Ltd. The book has been rewritten, 

 with additions in the form of hints and suggestions for experi- 

 mental work as a basis for the lessons. Elementary students of 

 chemistry are thus instructed in laboratory methods, as well as 

 given numerous arithmetical problems which will help to make 

 them understand the value of quantitative work. 



Vol. l No. 2 of the Records of the Botanical Survey of 

 India is entitled a "Note on the Botany of the Kachin Hills 

 north-east of Myitkyina." It is, however, more than a "note," 

 consisting of a record of the results of Lieut. E. Pottinger's 

 journey through this district of Burma. After some preliminary 

 general notes on the Botany of the Kachin Hills by Lieut. 

 Pottinger and Dr. D. Prain, a complete list is given of the 

 Flowering Plants and Vascular Cryptogams collected, the 

 district proving especially rich in Orchidese. A small map 

 is appended. 



Mr. Stanford has now concluded the arrangements for the 

 completion of the re-issue of his " Compendium of Geography 

 and Travel." The Europe volumes are in the hands of Mr. 

 George G. Chisholm, who has finished Volume i., comprising the 

 countries of the mainland (excluding the north-west), and has 

 Volume ii., covering the British Isles, Scandinavia, Denmark, 

 and the Low Countries, in hand. The volumes on Central and 

 South America have been entrusted to Sir Clements Markham 

 and Mr. A. H. Keane, and they will be furnished with the 

 usual maps and illustrations. Mr. Stanford hopes to complete 

 the issue of the series in the course of 1899. 



From the United States we have the following botanical 

 publications of taxonomic interest : — Revision of the Mexican 

 and Central American species of Galium and Relbtmitirn ; and 

 Diagnoses of New and Critical Mexican Phanerogams, by J. 

 M. Greenman (Contributions from the Gray Herbarium of 

 Harvard University) ; also Onagrace^ of Kansas, by Prof. A. 

 S. Hitchcock, with sketch-maps of the distribution of each 

 species (in French and English, published at Le Mans). And 



