yan. 24, 1878] 



NATURE 



253 



have been executed in an artistic manner and give a clear idea of 

 the variety of destructive agencies resorted to by mankind for 

 warlike purposes. 



We have received a useful little manual of dates, " Drury's 

 Chronology at a Glance" (Hardwicke and Bogue), containing 

 much well-packed information. In the next edition the author 

 should omit all expression of opinion on events and men, and 

 utilise the space for additional information. 



In the January number of Petermann's Mittheilungen, Dr. 

 Mohn describes in detail the results as to soundings and tem- 

 peratures of the Norwegian North Sea Expedition* of 1876. 

 Dr. Oscar Drude has an important article on the geographical 

 distribution of palms, and a detailed programme is given of the 

 new expedition of Gerhard Rohlfs, to which we referred last 

 week. A brief sketch is given of the ten-years' exploration in 

 South America of Doctors Reiss and Stiibel, some of the results 

 of which have appeared at various times in Globus and else- 

 where, but the full details of which will necessarily ^take some 

 time to publish. 



Dr. Radde, in a letter from Tiflis to Dr. Petermann, speaks 

 of the brothers Brotheus, from Helsingfors and Wasa, who spen 

 last summer in botanising in the Caucasus, taking back with 

 them a varied collection of mosses and a rich herbarium of 

 phanerogams. 



The additions to the Zoological Society's Gardens during the 

 past week include a Javan Chevrotain ( Tragulus javanicus), a 

 Stanleyan Chevrotain (Tragulus stanleyanus), from Java, pre 

 sented by Mrs. Leslie Walker ; a Grivet Monkey {Cercopithecus 

 griseo-viridis) from North-East Africa, presented by Madame 

 Patey ; an Arabian Gazelle {Gazella arabica) from Arabia, 

 presented by Mr. Mark Whyley ; three Summer Ducks 

 {Aix sponsd) from North America, presented by Lord Bray- 

 brooke ; two Mandarin Ducks {Aix galericulata) from China, 

 two White-bellied Storks {Abdimia sphenorhyncha) from 

 West Africa, purchased ; two Silky Cow Birds {Molothrus 

 bonariensis) from South America, a Superb Tanager {Callisie 

 fastuosa), two Violet Tanagers {Euphonic violacea) from Brazil, 

 deposited. 



NEW FORM OF GAS-HOLDER 



T-J AVING found the necessity of a gas-holder which should 

 yield at steady flow of gas and be under control from the 

 lecture-room, at some distance from the only available spot where 

 the gas-holder could be placed, I devised the following plan, 

 which was carried out for me by Mr. Yeates, to whom I am 

 indebted for one or two excellent suggestions. The arrangement 



is, I believe, novel, it is inexpensive, and it answers admirably ; 

 it may, therefore, be of convenience to put before some of your 

 readers the following sketch, which needs but little explana- 

 tion : — 



A is a bell -shaped, gas-tight holder of galvanised iron or stout 

 zinc. B is a water-supply cistern with adjustible ball-cock valve, 

 in fact, an ordinary kitchen boiler supply-cistern, in connection 

 with the water-main through v. c is a small reservoir fixed to 



the dome of the gas-holder ; when filled, once for all, the water 

 oveiflows into the holder; to avoid j-plashing it is better to 

 convey a pipe, D, near to the bottom of the holder. The water- 

 pipe from the cistern, B, passes air-tight into the gas-holder, and 

 is furnished with a cock, H, to shut off the pressure when neces- 

 sary. The pressure en the gas within the holder obviously 

 depends on the difference of the water-level in the cisterns B and 



J/? 2' 



C. To give a brilliant lime- light some ten inches head of water is 

 required. Tfiis corresponds to about 2 cwt. on the usual wedge- 

 shaped gas-bag. To give a sensitive flame with a steatite gas-jet 

 having an orifice the size of No. 19 wire, B v^r G (0-04 inch 

 diameter), a pressure of some nine inches of water is required. 

 The depth of the cistern, b, allows the ball-float a range of 

 adjustment, and hence of gas-pressure, of some six inches. 



