November 17, 1898] 



NATURE. 



61 



Uunty summaries, showing by means of tables the output of 

 ! ich county. This will prove of great service to those who are 

 lecially interested in the welfare of any particular county. 



From Prof. Kr. Birkeland we have received a reprint of a 

 iper by him in the Archives des Sciences physiques et 

 iturelles, on the phenomena of attraction or " suction " of 

 ithodic rays by a magnetic pole. Since the author's previous 

 iper in 1896, the subject has been treated from a theoretical 

 andpoint by Poincare, whose views have been put to an 

 cperimental test in a recently published paper by Wiedemann 

 id Wehnelt. In the meantime Prof. Birkeland has made a 

 ew series of experiments on the subject, and his present paper 

 3t only affords a completion of Wiedemann and Wehnelt's 

 ivestigation, but furnishes a simple method for determining 

 le relation existing between the velocity of the kathodic rays 

 id the difference of potential (between anode and kathode) 

 ider which these rays are emitted. 



I Mr. B. G. Teubner, of Leipzig, has commenced to bring 

 I lit a new and important mathematical work in German, en- 

 tled the " Encyclop.aedia of the Mathematical Sciences." 

 I 'he object of the Encyclopaedia is to give in a concise form but 

 (ith the greatest possible completeness, and in a manner adapted 

 j>r easy reference, all the newest results in both pure and 

 pplied mathematics. It is also proposed to show by carefuUy- 

 repared literary sketches, the historical development of mathe- 

 liatical methods since the beginning of the century. The 

 (ncyclopaedia will consist of six volumes, of about 3840 

 pges, of which the first will treat of Arithmetic and Algebra ; 

 ;ie second, of Analysis ; the' third, of Geometry ; the fourth 

 iid fifth, of Applied Mathematics ; and the sixth, volume of 

 istorical and allied matter. In the detailed table of contents 

 le absence of any reference (specific or indirect) to " Trigo- 

 lometry" or "Circular Functions" is somewhat remarkable, 

 being that even such a subsidiary subject as "Inversion" has a 

 [hole section devoted to it under Geometry. The editors are 

 !)r. H. Burkhardt (Zurich) and Dr. W. Franz Meyer (Konigs- 

 •erg), and the work is being published under the auspices of 

 lie Imperial and Royal Academies of Munich and Vienna and 

 /le Royal Society of Gottingen. From the prospectus we learn 

 hat " lengthy demonstrations will in general be omitted." 



The French Meteorological Office has recently issued its 

 \iina/es for 1S96, comprising three large quarto volumes. The 

 rst volume, under the title of " Memoirs," contains a discussion 

 ly M. Fron of thunderstorms observed during the year, with 

 (harts showing their distribution for each day on which a storm 

 occurred. M. Moureau publishes the details of the magnetic 

 Ibservations at Pare St. Maur, with a summary of the character- 

 kicsof the principal disturbances. These and the simultaneous 

 jariations of earth currents are also shown by means of curves, 

 "here is an important work by M. Brillouin on contiguous 

 Unds and clouds, in which the author studies the very compli- 

 lated phenomena that may be produced in a region where two 

 ;tmospheric strata mix together, and in which the amount of 

 iloud is unequal. M. Angot discusses the problem of the 

 krometric measurement of heights, and has prepared new 

 ables to facilitate the calculations. The attention of scientific 

 lien has been drawn to this question by the observations made 

 luring recent international balloon ascents. A contribution to 

 he rainfall of the region of the Upper Nile is made by M. de 

 ilartonne. Monthly and yearly values are given for some forty 

 tations, collected from various sources. There are also other 

 lapers of a minor character. Vol. ii. contains the results of 

 ibservations made at various stations. The colonial stations 

 lave been considerably extended, especially in Africa, and some 

 bservations are given for Timbuctoo, in the centre of that con- 

 NO. 15 16, VOL. 59] 



linent. \'ul. iii. is devoted entirely to the discussion of rainfall 

 observations : the number of stations included in the work 

 exceeds two thousand. 



In connection with the journal Photoip'aphy, silver and bronze 

 medals are offered for the best sets of lantern slides relating to 

 the subjects named in the following sections: — (i) The rivers 

 of Great Britain ; (2) the commercial ports of Great Britain ; 

 (3) the old churches of the United Kingdom ; (4) British trees, 

 plants, and flowers ; (5) scenes among fishermen ; (6) striking 

 natural scenes in Great Britain (rocks, caves, trees, waterfalls, 

 &c. ). The competing slides should be in the hands of the 

 editors by December 10. The object of the competition is to 

 renew sets of similar slides which have for several years been 

 circulated by Photography, without charge or fee, and have been 

 largely used in schools for purposes of instruction. 



Two papers on the food of certain cuckoos and shrikes, based 

 on investigations by Prof. F. E. L. Beal and Dr. S. D. Judd, 

 are contained in Bulletin No. 9 of the Division of Biological 

 .Survey (U.S. Department of Agriculture). In the laboratory 

 of the Biological Survey 109 stomachs of the yellow-billed 

 cuckoo {Coccyzus niiiericanus), and forty-six of the black-billed 

 cuckoo ( C. crythrophthahiiHs), taken between May and October, 

 were examined. The results show that of the 155 stomachs of both 

 species only one contained any vegetable food. It appears that 

 the insect food of these birds consists of beetles, grasshoppers, 

 cicadas, bugs, ants, wasps, flies, caterpillars, and spiders, of 

 which grasshoppers and caterpillars constitute more than three- 

 fourths. The great majority of the insects found in the 

 stomachs were harmful kinds. It is a matter of common ob- 

 servation that cuckoos feed largely on caterpillars, and stomach 

 investigations not only confirm this, but show that, unlike most 

 other birds, they eat freely of hairy and bristly species. Nearly 

 half of the food of the birds examined was found to be caterpillars. 

 Considering the number of grasshoppers, locusts, and other 

 insects that cuckoos eat, in addition to caterpillars, it is evident 

 that from an economic point of view these birds are two 

 most valuable species, and as they have not been con- 

 victed of doing any harm, they should be protected and en- 

 couraged in every possible way. Besides insects proper. Prof. 

 Beal found a number of spiders in the stomachs he examined, 

 most of the m the long-legged kinds commonly known as 

 "daddy longlegs " (Phalangidae). One stomach contained 

 seven, the mass of tangled legs looking like a bunch of coarse 

 hair. When we consider the disagreeable odour of these 

 spiders, their long legs, and the fact that their bodies have the 

 texture of sandpaper, we are again forcibly reminded that tastes 

 differ. But the most remarkable thing which the birds examined 

 had eaten was a small tree frog {Hyla). which had been swallowed 

 whole ! 



Dr. S. D. Judd investigated the food of two species of 

 shrikes, and the results are given in the Bulletin referred to in 

 the foregoing note. One species, the loggerhead shrike {Lctnius 

 ludovicianus et sub-spec.) is a permanent resident of the United 

 States; the other, the butcherbird {Lanius iorealis), is a migrant 

 from the north. From the investigation it appears that the food 

 of the butcherbird and loggerhead, as shown by 155 stomachs 

 collected during every month in the year, and in an area extend- 

 ing from California to the Atlantic coast, and from Saskatchewan 

 to Florida, consists of invertebrates (mainly grasshoppers), birds, 

 and mice. Daring the colder half of the year the butcherbird 

 eats birds and mice to the extent of 60 per cent., and ekes out 

 the rest of its food with insects. In the loggerhead's food, birds 

 and mice amount to only 24 per cent. A table showing per- 

 centages of principal elements of food of the butcherbird and 

 loggerhead indicates that the loggerhead's beneficial qualities 



