304 



NATURE 



[January 28, 1892 



in districts where cattle-rearing is the principal industry. Their 

 maximum appearance depends very much on the season and 

 othor circumstances not yet fully worked out. In tropical 

 countrie-! nearly everywhere there are formi locally called ticks, 

 but evidently allied to the harvest-bugs of Europe. These are 

 called by the French Roiigct, and in the West Indies Bete rouge. 

 They are supposed to be larval forms of Trombidum, and 

 are not ticks in the usual acceptance of the term. One re- 

 markable power possessed by the Ixodidce is that of existing 

 for a great length of time without food. Specimens have been 

 known to live for years accidentally shut up in a small box. Sir 

 Joseph Hooker, in the "Himalayan Journals," recently reprinted, 

 states (p. 196), "that ticks were present everywhere in the hill 

 forests"; and he remarks: "What ticks feed upon in these 

 humid forests is a perfect mystery to me, for from 6000 to 9000 

 feet they literally swarmed where there was neither path nor 

 animal life." In attacking man and animals ticks insert the 

 proboscis deeply without pain. Buried head and shoulders, and 

 retained by a barbed lancet, they are only to be extracted by 

 force, which is very painful. At present very little is known of 

 \.\\&Ixodid(z of tropical America. It is possible there may exist 

 numerous species, each with its own special life-history. No 

 one appears as yet to have given undivided attention to the 

 group, and possibly less is known of ticks from a scientific point 

 than any other members of the West Indian fauna. In view of 

 the influence of their occurrence on man and animals this is 

 somewhat anomalous. 



M. Jean Dybowski contributes to the current number of 

 La Nature a sketch of a journey he has made from Loango to 

 Brazzaville, and from thence to Bangui. He has collected many 

 objects of scientific interest, including 480 ethnographic speci- 

 mens, 550 botanic specimens, 280 birds, 100 mammifers, reptiles, 

 fishes, insects, &c. 



Several shocks of earthquake were felt at Rome on the 

 evening of January 22. According to a telegram sent through 

 Reuter's Agency, they caused such a panic in the more crowded 

 quarters that many of the inhabitants fled from their houses, and, 

 notwithstanding the cold weather, spent the night in the streets 

 and public squares. The shocks were felt in the theatres, but the 

 panic there was of short duration. The seismic disturbance had 

 a distinct effect upon the clocks, some stopping at 11.25, ^nd 

 others at 11.27. Several of the lamps in the streets were ex- 

 tinguished. The shocks were noticed by the Pope, who sent 

 to the Vatican Observatory to make inquiries. They were very 

 generally felt throughout the province of Rome. At Genzano 

 a few houses fell in, but no one was injured. At Civita Lavinia 

 an old tower, dating from the Middle Ages, fell and buried two 

 persons, who were, however, promptly extricated. Several 

 houses are in a dangerous state. A severe shock was also 

 experienced at Velletri, but the damage done was insignificant. 



According to the Paris correspondent of the Daily News, 

 two slight earthquake shocks were felt on Sunday, January 24, at 

 Le Mans, the centre of an important agricultural district in the 

 west of France. At Sarce, about 2 a.m., the villagers were 

 awakened by a rather severe shock which caused the school bell 

 to ring. At Chateau du Loir, a town on the State railway line 

 from Paris to Bordeaux, the first shock lasted three seconds, 

 and awakened everybody. The second took place at half-past 

 three, and was slight. 



The U.S. Monthly Weather Review for October 1891, con- 

 tains a continuation of curves previously published, showing the 

 fluctuations of temperature and pressure at the base and summit 

 of Mount Washington (altitude 6279 feet), and completes them 

 for the months January to March from 1871-86, or for 16 years, 

 with a short discussion by Prof. H. A. Hazen. The base 

 curves show many minor fluctuations of temperature not to be 

 NO. I 161, VOL. 45] 



found in the summit curve=, most of which are probably due to 

 diurnal range, but as regards the larger fluctuations the most 

 marked characteristic in the temperature curves has been their 

 closeness at base and summit. The earlier change at the summit 

 in both cold and hot waves is remarkable. The fluctuations of 

 pressure are almost identical at the base and summit. Occa- 

 sionally, the change in temperature at the summit has preceded 

 that in pressure to such an extent as to cause the phases of the 

 latter to lag behind. The curves have been published in the 

 hope that meteorologists will make a special study of them. 



It is a well-known fact that, with the same temperature 

 by the thermometer, one may have, at diff'erent times, a 

 very diff'erent feeling of heat or cold. This varies with the 

 temperature of the skin, which is chiefly influenced (according 

 to M. Vincent, of Uccle Observatory, Belgium), by four 

 things : air-temperature, air-moisture, solar radiation, and force 

 of wind. M. Vincent recently made a large number of observa- 

 tions of skin-temperature in the ball of the left hand, and con- 

 structed a formula by means of which the skin-temperature may 

 be approximately deduced from those four elements. He 

 experimented by keeping three of the four constant, while the 

 fourth was varied, and a relation could thus be determined 

 between the latter and skin-temperature. One fact which soon 

 appeared was, that the relative moisture of the air has but little 

 influence on skin-temperature. It was also found that for every 

 1° C. of the aclinometric diff'erence (excess of black bulb ther- 

 mometer) the skin- temperature rises about o°'2 ; and with 

 small wind- velocities, every metre per second depresses the skin- 

 temperature about i°"2. In testing his formula, M. Vincent 

 found, with cold or very cold sensation, considerably greater 

 differences between the calculated and observed values than in 

 other cases. This he attributes to the great cooling of the 

 relatively small mass of the hand. Taking the cheek or eyelid, 

 the results were better. He constructs a scale of sensations 

 corresponding to different skin-temperatures as he found them 

 (which scale would, of course, vary somewhat with individuals). 



Last winter, in December and January, M. Chaix made 

 a number of observations of the temperature of the air, the 

 snow, and the ground, at Geneva ; of which he has given an 

 account to the Physical Society there. He observed the air at 

 four different heights ; granular, pulverulent, and bedded snow, 

 on the surface and at different depths ; and the surface of bare 

 ground as well as of ground covered with snow. There was no 

 difference in mean temperature between the air at i and at 2 

 metres ; and very little between the former and that on the 

 snow surface. The surface of the ground was 4° 265 C. warmer 

 than the surface of the snow (0'I3 m. above), through arrest of 

 radiation. But the bare ground was not cooled so much as the 

 snow surface, and it was only 2°*04 colder than the snow- 

 clad ground. This shows the frigorific influence of snow on 

 climate. Air passing over bare ground would have been 2° 

 warmer than if it passed over the snow. The snow surface 

 was sometimes warmer, sometimes colder, than the air i or 2 m, 

 above. In the dry winters of Siberia and Sweden, the snow - 

 surface is generally (according to Woeikof) much colder than 

 the air. M. Chaix explains the variations observed at Geneva 

 by fluctuations in the relative humidity, involving alternate 

 vaporization and condensation at the snow surface. In two- 

 thirds of the cases, indeed, abnormal cooling of the snow 

 corresponded with a low humidity, and heating with a high 

 humidity, and often formation of hoar frost at the surface. 



An interesting paper on Prof. Wiborgh's air-pyrometers was 

 read by Mr. John Crum before the Institution of Engineers and 

 Shipbuilders in Scotland on December 22 last, and is now 

 printed in the Institution's Transactions. Beginning at the 

 beginning, Mr. Crum explained that a pyrometer is an instru- 



