2S6 



NA TURE 



[January 12, 1899 



forming an X is brought into coincidence with the given fixed 

 line ; in the second, one wire is superposed on the line ; 

 in the third, this line bisects the space between two parallel lines ; 

 and in the fourth, the reference line is adjusted at one side of the 

 movable parallel lines at a distance from one of them equal to 

 their distance apart. Four observers were selected, each being 

 required to make twelve settings with either arrangement ; 

 firstly with time unlimited, secondly with time limited to two or 

 three seconds, and thirdly with each of the four settings taken 

 in alternation. The probable error of the mean of each group 

 of twelve observations was calculated by the Theory of Least 

 Squares. With one exception the method of intersecting wires 

 is found to give by far the largest probable error, and may easily 

 be classed as the poorest method. When the reference mark 

 upon which the wires are to be set is of the same order of mag- 

 nitude as the movable wire, the method of superposing one upon 

 the other gives the best results. Lastly, when the reference 

 mark is larger, such, for example, as the lines on a graduated 

 scale, the third or fourth method should be used, the choice 

 between these two depending upon the observer. It is thus re- 

 markable that the cross-wire arrangement adopted in the 

 older transit circles should be so inferior to other arrangements. 



In some notes on the geology of Syria [Bericht der Senckeiih. 

 naturf. Geselhih., Frankfurt, 1S9S), Dr. F. Kinkelin records 

 fossils from the Cretaceous and Eocene formations in a number 

 of localities. It is well known that in Palestine strata from 

 the base of the Upper Cretaceous to the Nummulitic limestones 

 form one great geological group, and it may be judged from 

 the facts made known by Dr. Kinkelin that a corresponding 

 series occurs in northern and central Syria. A new species 

 {Cardiiim Dayi) is described from strata yielding Inoceramus 

 (omenlricns and Vola (Peclen) aeqtikostala. 



Remains of fossil Jerboa (Alactaga saliens fossilis) have 

 been described, by Dr. A. Nehring, from the Pleistocene strata 

 of Westergeln, between Magdeburg and Halberstadt {N. 

 fahrbuchf. Mineralogie, ^c, 1898, Bd. II.) 



The development of the pattern of the wings of butterflies in 

 the pupa forms the subject of a paper by Countess M. von 

 Linden, in the Zcitschrift fiir wissetischaftliche Zoologie, Band 

 65, Heft I. The principal species discussed, and illustrated in 

 the three plates which accompany the article, are Papilio 

 podaliriiis land iiiachaon, T/iais polyxciia, and Vanessa levaim 

 and urticac. This paper is followed by one upon a similar 

 subject, by Dr. M. Baer, who discusses the structure and color- 

 ation of the wing-scales in butterflies. The author recognises 

 three different classes of colour, viz. (i) pure colours, due ex- 

 clusively to pigment ; (2) optical colours, due to refraction ; 

 (3) mixed colours, due to the effects of pigment and refraction 

 combined. 



The Proceedings of the tenth annual meeting of the Asso- 

 ciation of Economic Entomologists (U.S. Department of 

 Agriculture, Division of Entomology, Bulletin No. 17, New 

 Series) include a variety of short papers on insects of various 

 orders, and the best means of destroying them. Prof. Howard's 

 observations on the ease with which Chalcid parasites of 

 Coccidae can be introduced from one country to another, are of 

 considerable importance. There is also a paper by Mr. T. D. 

 A. Cockerell, on "Entomological Ethics," containing some 

 suggestions which may not be unworthy of the attention of 

 those who are responsible for the management of museums and 

 other public collections. 



Amongst the botanical papers read at the last meeting of the 

 American As-sociation for the Advancement of Science is one 

 by Dr. Erwin F. Smith, describing some observations he has 

 made on an organism recently isolated from and believed to be 



NO. 1524, VOL. 59] 



responsible for a disease which appears in sweet corn. It was 

 originally found by Stewart occurring in enormous numbers in 

 the vascular bundles of corn, making ^he leaves flabby ■ 1 

 shrivelled. It is a motile bacillus and is provided with on 

 polar flagellum, and grows in all ordinary culture media, pro- 

 ducing a yellow colour both in the latter and in the host plant. 

 It grows best in the presence of cane-sugar, and very striking 

 difierences are observed when it is inoculated on to slices of 

 turnips and slices of beetroot respectively, the growth being ten 

 to fifty times as abundant in the case of the latter. In this 

 characteristic may possibly be found an explanation of why 

 sweet corn is attacked in preference to common corn. It has 

 been found in New York and Michigan States, and may be 

 looked for, says its discoverer, in all parts of the United Slates. 



Dr. G. Agamennone has contributed to the Aiti dei Lineei 

 (vii. II) some interesting statistics relating to the earthquake 

 at Hayti on December 29, 1S97. The position of the epi- 

 centre was roughly in latitude I9J°N., longitude 71" W. As 

 mentioned in a former note in Nature, Dr. Agamennone had 

 previously found considerable difficulty in calculating the velocity 

 of propagation of the Labuan shock, which he attributed to the 

 differences in sensitiveness of the instruments by which it 

 was recorded at various stations. That this explanation was 

 the correct one, is confirmed by analogous observations con- 

 nected with the Hayti earthquake. Thanks to the existence of 

 a Cecchi seismograph at Port-au-Prince, whose readings could 

 be compared with those taken at Catania and Ischia, the 

 velocity of propagation of different waves was calculated, and 

 was found in no case to reach 10 kilometres per second ; and 

 the swiftest waves, probably longitudinal in character, were 

 followed by waves of long period whose superficial velocity 

 seems to have averaged 3 kilometres per second. But it is 

 pointed out that in the absence of the Port-au-Prince Observatory, 

 a comparison of the records made at Toronto and in Europe 

 would have given improbably high values for the velocity of 

 propagation, consequent upon the Toronto instrument being 

 insensible to the first waves which affected the Europeai> 

 seismographs. 



The buildings of Oxford, from an engineer's point of view, 

 form the subject of an illustrated article in the January number 

 of the Engineering Magazine. 



A BRILLIANT heliogravure of Dr. Sidney Coupland, recently 

 appointed Commissioner in Lunacy, appears in the Mida'lese.x. 

 Hospital Journal. Dr. Coupland has been connected with 

 Middlesex Hospital for many years, in the department of 

 pathological anatomy. 



An instructive description of the great boulder of gypsum, 

 recently found at Great Crosby, is given by Mr. T. .Mellard 

 Reade in a pamphlet, a copy of which has been sent to us. A 

 picture of the boulder upon the pedestal erected for it by the 

 District Council of Great Crosby, forms the frontispiece of the 

 pamphlet. 



The new volume of the Geographical Journal, contaiiiing the 

 six monthly parts from July to December 1S9S, has been pub- 

 lished. Like previous volumes, the present one is filled with 

 interesting papers read before the Royal Cleographical Society, 

 articles on topics of geographical importance, a monthly record 

 of contributions lo geography in various parts of the world, ark 

 invaluable bibliography of current geographical literature, lists 

 of new maps, and numerous coloured maps lo illustrate the 

 contents. 



A COPY of the second number of the Zambesi .Mission Record 

 has been sent to us. The periodical is to be published about 

 four times a year, and is concerned with the C.uholic missions in 



