590 



NA TURE 



[April 19, 1900 



Guinea) might be collected into a Melanesian sub-region, and 

 subordinated to the Oriental Region. Since I have elaborated 

 these views in another place, I will here limit my argument tea 

 couple of supporting references. 



(i) When Dr. Wallace first returned from his Eastern travel 

 his impression of a natural region was one "extending from the 

 Nicobars in the north-west to San Christoval, one of the 

 Solomon Islands, on the south-east, and from Luzon on the 

 north to Rotti, at the south-west angle of Timor, on the south " 

 (Report British Assoc. 1863, Traits, p. 107). 



(2) Dr. W. Bolting Hemsley has stated : " There is no doubt 

 that the combined Fijian, Samoan and Tongan flora is eminently 

 Malayan in character " {Journ. Linn. Soc. Botany, xxx. p. 211). 



To map New Zealand thus as an extreme and impoverished out- 

 lier of the Oriental or Malayan Region would express but a part 

 of her affinities, since it would ignore the Antarctic relationship. 

 But zoo-geographic problems are too complex to be expressed 

 in terms of colour on a map. If, however. New Zealand and 

 related areas must be forced into one or other of the recognised 

 divisions, then I submit that this arrangement would do less 

 violence to nature than that accepted in the text-books. 



Australian Museum. Charles Hedley. 



Mercury Jet Interrupters. 



My attention was attracted recently by a brief notice that 

 appeared in Nature of March i (p. 421) of a new form of 

 mercury jet interrupter devised and placed on the market by 

 Messrs. Isenthal, Potzler and Co. 



As that form of break appeared to be of interest to the readers 

 of Nature, a short description of one that I designed some 

 months ago, along similar lines, may be of interest to some. 



While experimenting with wireless telegraphy an interrupter 

 of great frequency of break seemed desirable, and as I wanted 

 also to know the rate of interruption accurately, it was deemed 

 best to use some form of mechanical one. After investigating 

 several kinds, the following one was finally decided upon as 

 the most promising : — 



. An iron vessel, arranged as a Mariotte flask to maintain a 

 constant head, holding about a pint of mercury, formed one 

 terminal and a metallic plate the other. The plate was arranged 

 below the vessel, and the mercury fell upon it, completing the 

 circuit. In the bottom of the flask was a row of ten holes, 

 arranged around in a circle, with nozzles fitted into them. On 

 a vertical shaft, concentric with the row of nozzles, a series of 

 mica sectors were arranged, so that, when revolving, they would 

 cut the mercury jets falling from the vessel above. These strips 

 were placed with the line of their edges parallel to the axis of 

 the shaft. Thus they would break the circuit in several places 

 at the same instant, giving a very sharp break. 



It was found better to break the circuit by interposing an 

 insulator than to break by opening the circuit with a conductor, 

 as the wear at the spark tended to keep them all equal, so 

 they automatically adjusted themselves to the best positions. 



The object of the row of jets was to get a more rapid inter- 

 ruption. To break a single jet in five or six places simul- 

 taneously, and at the same time with a satisfactory frequency, 

 was found to require too great a head and velocity of jet to be 

 practicable, so by adopting a row of ten the frequency could 

 be increased that many times. These jets are all in parallel, 

 and when the mica strips are revolving the head is so adjusted, 

 by the Mariotte flask arrangement and screws on the sides of 

 the reservoir, that at the instant of interruption of one jet, all the 

 others are in a state of interruption ; but the one directly in 

 front of the mica strips will be the first to make the circuit. 

 Thus it continues to break at a rapid rate. 



Greater rapidity of break can easily be obtained by increasing 

 the speed, by increasing the number of nozzles, by increasing 

 the number of sets of mica strips, or by any combination of the 

 three. 



This form of interrupter will be found quite useful to any one 

 desiring a known rate, high frequency interrupter. 



S. M. Kintner. 



Western University of Penna, Allegheny, Pa., April 2. 



Tyndall's Ice Crystals. 



Would you, or some of your readers, kindly inform me 

 whether the ice crystals, as shown in Tyndall's "Form of 

 Water," p. 33, are considered to represent skeleton crystals 

 or solid ones arranged in patterns ? J. A. 



Tunbridge Wells, April 14. 



NO. 1590. VOL. 6j] 



MARINE ZOOLOGY IN AUSTRALIA.^ 

 T N these columns was noticed recently the admirable 

 -*■ activity of the various Australian museums in 

 making known to science the natural objects of southern 

 lands and seas. On that occasion it was an important 

 addition to our knowledge of mammalian palaeontology 

 — Prof. Stirling's description of Diprotodon remains — 

 that was especially under discussion. Now we have ta 

 record equally important investigations in marine zoology 

 undertaken by the staff of the Australian Museum, 

 Sydney. 



Besides "guides" and "miscellaneous publications," 

 the Sydney Museum issues a series of "records" for 

 minor papers ; " catalogues," which are large and fully 

 illustrated, contain descriptions of many new species, 

 and are really in some cases monographs ; and 

 " memoirs," such as the natural history of Lord Howe 

 Island (1889); that on the Atoll of Funafuti more 

 recently, in ten parts ; and, finally, the " Scientific Results 

 of the Trawling Expedition of H.M C.S. Thetis" of 

 which Part i. is now before us. P'rom the introduction, 

 by Mr. Edgar R. Waite, we learn that this expedition 

 was the outcome of a desire on the part of the Govern- 

 ment of New South Wales to investigate the trawl 

 fisheries of their coast. In 1898 H.M. C.S. Thetis was 

 commissioned, the expedition was financed by the 

 Colonial Government, and an experienced North Sea 

 trawler was obtained, upon whose skill depended the 

 successful working of the apparatus. Finally, the 

 Trustees of the Australian Museum were asked to 

 appoint one of their officers to join the expedition, and 

 Mr. Waite was selected to act in that capacity. He 

 tells us how a large and valuable collection was obtained 

 and preserved (not without considerable difficulty, as 

 experience showed that the Thetis was a most unsuitable 

 vessel for the purpose), and promises that the various 

 groups will be dealt with in detail by members of the 

 museum staff in succeeding parts of the memoir. An 

 "Addendum to the Introduction" on fishing with electric 

 light— not yet brought to perfection— concludes with the 

 sentence : " I lowered an incandescent lamp in a tow- 

 net, and obtained a number of small invertebrates, thus 

 reproducing the experiments conducted at the Liverpool 

 Biological Station" (p 132). He does not tell us what 

 the forms were which were obtained in the illuminated 

 net. In the Liverpool experiments they were all actively 

 swimming forms provided with eyes. i 



The remainder of the present part contains Mr. Waite's ' 

 report upon the fishes. One hundred and seven species- ■ 

 were taken, representing ninety-five genera, including \ 

 one new genus, viz. Paratrachichthys (formed for J 

 Trachichthys trailli, Hutton). Nine new species are '^ 

 described, a number of others are new records for the : 

 colony. But it is very evident that, as Mr. Waite says, | 

 "the interest of the results is, however, not exhausted | 

 by an enumeration of the new or rare species ; the ex- | 

 pedition has been the means of materially extending the \ 

 known range,both geographically and vertically, of several ; 

 of our common food fishes. The breeding season of one ■ 

 or two species has been ascertained, . . . and our know- 

 ledge of the habits of the soles has also been extended." \ 

 As the trawling was for the most part not carried on in j 

 really deep water, but within the limit reached by line ^ 

 fishermen, the scientific and economic success was all the \ 

 more marked. As an example of the latter may be taken j 

 the information as to Zeus aiistralis, a rare and valuable j 

 food fish, which was found under circumstances mdi- ; 

 eating that it may yet take its place as a popular and \ 

 cheap food fish. ! 



Of the nine new species described, perhaps the most | 

 interesting is the "ghost-shark" {Chimaera ogilbyi\ ; 



1 Australian Museum, Sydney. Memoir IV. " Scientific Results of the ■ 

 Trawling Expedition of H.M. C.S. Thetis," &c. Part 1. Pp. 132 ; 3» ; 

 plates, frontispiece, and a chart. (Sydney, 1899.) ' 



