2l6 



NATURE 



\July 6, 1876 



the two latter. In his second paper Prof. Wyville Thomson drew 

 attention to peculiarities in the mode of propagation of certain 

 Echinoderms of the Southern Sea. He passed in review examples 

 of the Sea-cucumbers {Holothuroids), Sea Urchins (the circular 

 Cidaroids, and heart-shaped, Spatangoids), Star-fish (Asteroids), 

 and the Brittle Stars [Ophiuroids). In allusion to their phases of 

 development he stated the majority of these pass from the egg 

 without the intervention of a locomotive pseudembryo. Among 

 other data in support of this view he said, that while in warm and 

 temperate seas " plutei" and "bipinnari " were constantly taken 

 in the surface-net ; yet during the southern cruise between the 

 Cape of Good Hope and Australia, only one form of Echinoderm 

 pseudembryo occurred, and which was considered with some 

 little doubt as the larva of Chirodota from the presence of dermal, 

 calcareous, wheel-shaped spicules. Furthermore Prof. Wyville 

 Thomson described in detail the almost constant occurrence among 

 the majority of the foregoing groups a curious, receptacular pouch 

 wherein the young are carried until arriving at a certain maturity. 

 This marsupium is situated on the dorsal portion of the body, is 

 composed of a series of plates which meet centrally and permit 

 of the young creeping about and returning to it for shelter. The 

 young derive no nutriment from the parent while contained in 

 the " nursery," other than it may be a mucous secretion. 



THE U.S. WEATHER MAPS^ 



I N this fourth contribution to meteorology, Prof. Loomis dis- 

 cusses certain points of a miscellaneous nature which have 

 been either very slightly or not at all examined in his three 

 previous contributions. The movements of areas of high baro- 

 meter, which are of so great importance in their relations to 

 weather and climate, have been examined with the result that 

 while the average track of areas of low pressure across the 

 United States is nine degrees to the north of east, the track of 

 areas of high barometer advance toward a point several degrees 

 south of east, and with a velocity somewhat less than the 

 former. 



As regards the conditions under which the monthly minima of 

 temperature occur, it is shown that these conditions, viz., winds 

 very light, sky clear, and pressure above its mean height, are 

 substantially the same at Jakutsk, Siberia, as at New Haven. 

 Prof. Loomis is of opinion that it is true universally that periods 

 of unusual coM are generally accompanied by a barometer above 

 the mean, and by a descent of air from the upper regions of 

 the atmosphere. These areas of high barometer have a broader 

 significance than is here implied. It is the still, clear, and dry 

 atmosphere accompanying them, and its relations to terrestrial and 

 solar radiation, which afford the conditions of extreme tempera- 

 tures. The monthly minima of the cold months of the year 

 and the maxima of the warm months both frequently occur under 

 the conditions afforded by areas of high pressure. On the other 

 hand, in North-western Europe it is often observed that the 

 minima of temperature during the warm months repeatedly occur 

 within areas of low pressure where very I'ght easterly and 

 northerly winds prevail. In discussions of the relations of tem- 

 perature and pressure, it is seldom kept steadily in mind that the 

 given temperature is merely the temperature observed within a 

 few feet of the earth's surface, which, as regards areas of high 

 pressure, will nearly always mislead if it be used as a basis from 

 which to estimate the temperature of the higher strata vertical 

 to it ; the surface temperature being abnormally low in winter 

 from contact with the cooled surface, and in summer abnormally 

 high from contact wiih the heated surface of the earth. 



The examination of storm paths in America, the Atlantic, 

 and Europe is important from the bearing of the subjects on 

 climatology and weather-forecasting. Some interesting results 

 of such an examination are given by Prof Loomis in the average 

 paths marked on the chart accompanying the paper. The results, 

 however, are not calculated to be practically useful until the 

 average paths be laid down for each month in the year, owing 

 to the very great differences in these paths as regards different 

 months. Thus, in North-western Europe, during the spring 

 months, when east winds are most prevalent in Great Britain, many 

 storm tracks, or the course of barometric depressions, are more 

 southerly, and during the winter months more northerly than 

 that indicated on the chart. If the track of storm-centres in 



Results derived from an examination of the United States Weather 

 Maps and ether sources. By Prof. Elias I o .mis, Ya'e College. Fourth 

 Paper. From \\\.ti American "Journal of Science and Arts, soV xi,, }3.n. 

 1876. 



winter generaUy took the line of The Channel, our winters would, 

 on the average, be much more severe than they are, owing to 

 the greater frequency of easterly and noitherly winds, which 

 would necessarily follow. But open winters are the rule in these 

 islands, and even as far north as Faroe, where, during winter, 

 southerly and westerly winds largely preponderate, thus showing 

 that the central tracks of the majority of our winter storms lie to 

 the nor..h of Faroe. The exact determination of the average 

 monthly tracks and the more marked deviations from them 

 would throw light on several important questions affecting the 

 climatology of the whole of North-western Europe. 



Since the average velocity of storms over the United States 

 as deduced by Prof. Loomis from 485 cases, is twenty-six 

 miles per hour, and over the Atlantic, as deduced from 134 

 cases, is 19 '3 miles per hour, ard the average velocity of 

 European storms as deduced by Prof. Mohn is 26 "7 miles 

 per hour, it follows that storms travel less rapidly over the ccean 

 than over continents. If further inquiry confirms this result, we 

 have here a valuable contribution to the theory of storms which 

 will likely lead to a clearer insight into the causes which regu- 

 late their rate of propagation over the earth's surface, accelerat- 

 ing it in some cases, and in others retarding it as is frequently 

 seen off the coast of Newfoundland and in the Bay of Biscay. 



NATURAL SCIENCE AT CAMBRIDGE 



THE Cambridge Natural Science Tripos has just 

 entered upon a new phase of existence. The recent 

 examination is the first in which a division into two parts, 

 elementary and advanced, is carried out, the former being 

 held in June and the latter in December. Candidates 

 who do not satisfy the examiners in the first part are not 

 permitted to compete in the second. The final class-list 

 is to be based on the alphabetical principle, but the first 

 class will consist of two divisions, each arranged alpha- 

 betically, and the subject or subjects for which a man is 

 placed in the first class are to be indicated, while a spe- 

 cial mark will reward superior proficiency. This system 

 removes some of the worst faults of the competitive 

 system, and is of especial benefit to the more able men. 

 One subject will not be pitted against another as regards 

 marks, an accumulation of cramming in several subjects 

 will not serve an inferior man, and clear testimony will 

 be given that a man has a competent knowledge of a 

 subject, or that he is specially proficient in it. With such 

 arrangements, the value of the examination will largely 

 depend upon the wisdom of individual examiners. It will 

 be obvious that there should be at least two examiners in 

 each subject instead of one. Also the pittance they re- 

 ceive should be transformed into fair remuneration, which 

 will, no doubt, be done as soon as the University has 

 more funds at its disposal. 



It was to be expected that a new system, by which no 

 man receives any credit in a subject unless he shows 

 satisfactory knowledge of it, and by which the examina- 

 tion is limited to three days, would produce a large 

 number of failures to attain honours. The number of 

 candidates in June was forty- four, a large increase ; of 

 these only thirty-one obtained honours, while ten others 

 received the ordinary degree. On scrutinizing the papers, 

 it appears that there is a difficulty in equally adjusting 

 the questions which probably have affected the result. 

 Two questions in each subject, except human anatomy, 

 are given in every paper ; one question only is set in 

 human anatomy, which is introduced for the first time. I 

 will quote some of the questions in geology and in physio- 

 logy, giving fair samples ; and it will be plain that they 

 are not equivalent in difficulty, and that students of 

 moderate ability and reading might gain honours by 

 answering the former much more easily than the latter. 



" In which of the three great divisions of stratified 

 recks do fossils of the genera Ichthyosaurus, Phacops, 

 Calamites, Voluta, Terebratula, Ostrea, and Micraster 

 respectively occur ? " " Volcanic rocks have been di- 

 vided into two classes, acidic and basic. Give the name 

 and mineralogical composition of a common rock of each 



