io8 



SCIENCE. 



[Vol. XVI. No. 394 



Surgeon Parke on Vaccination. 



At the great banquet of welcome given in London to Surgeon 

 Parke, he briefly referred to the inestimable benefit of vaccina- 

 tion. Before the expedition started for Africa, says the Medical 

 News, he vaccinated nearly every man in Stanley's little army, 

 with the result that when they were surrounded by small-pox 

 there were only four cases among the members of the expedition, 

 none of which proved fatal. But among the camp-followers and 

 irregulars, who had not been vaccinated, small-pox was almost 

 universal, and large numbers of them died. It is probable that 

 without the precaution of vaccination the expedition would never 

 have had strength to complete the march across Africa. 



LETTERS TO THE EDITOR. 



*** Cor}-espondents are requested to be as brief as possible. The itrr iter's name 

 is in all cases required as proof of good faith. 



The editor will be glad to publish any queries consonant with the character 

 of the journal. 



On request, twenty copies of the number containing his communication will 

 be furnished free to any correspondent. 



Wind-Systems. 



The remarks on the general wind-systems of the globe on page 

 80 of Science for Aug. 8 are interesting. I liave been securing 

 from various mathematicians and meteorologists numerical state- 

 ments of the deflective force of the earth's rotation on moving 

 bodies on its surface. No two such statements thus far secured 

 agree with each other or correspond with the deflection of air- 

 currents actually depicted on the weather maps. As I understand 

 the communication above mentioned, there is substantial agree- 

 ment on the basis of the reasonings there presented that there is 

 neither eastward nor westward movement of the atmosphere at 

 latitude 35° 16'. It is true that the south Atlantic anti-cyclone is 

 located at nearly this latitude, and is quite persistent. But the 

 other anti-cyclones of the northern hemisphere, with reference to 

 which alone we have full information, are not located at this 

 latitude. On the contrary, they form a belt, not about the 

 geographical pole, but about a point situated twenty degrees from 

 it at longitude 96° west. In consequence of this displacement the 

 centre of this belt is found as far north as 55° in the eastern hemi- 

 sphere. Moreover, the separate anti-cyclones constituting it have 

 a decided tendency to move eastward. Even the south Atlantic 

 anti-cycloue pushes eastward not unfrequently at all seasons, and 

 either fragments are detached from it or it moves bodily across 

 Europe. At certain seasons this easterly movement of anti-cy- 

 clones is rapid, and at times appears to be independent of sur- 

 rounding cyclones. This would seem to be a feature of the circu- 

 lation of the atmosphere that is not consistent with the assumption 

 that there is absence of eastward or westward movement at lati- 

 tude 35° 16'. M. A. Veeder. 



Lyons, K.Y., Aug. 13. 



On the Lack of the Distance-Sense in Prairie-Dogs. 



Several individuals of various ages under observation at Cor- 

 nell University walked off chairs, tables, and window-sills with 

 nearly equal absence of hesitation. This deficiency of a faculty 

 which is so conspicuous with squirrels and some other rodents may 

 be ascribed to the nature of their usual habitat, a plain, in which 

 the only sharp inequalities may be the burrows and mounds of 

 their own making. 



One adult female, however, has manifested an immunity from 

 the ill effects of falls which is not easily accounted for, and may 

 be worthy of record. When about three years old it fell down a 

 shaft upon the wooden top of an elevator 6.6 metres (31.6 feet) 

 below. For a few minutes it remained nearly motionless, as if 

 stunned, but gradually revived and completely recovered. On the 

 14th of July, 1890, at the age of 7* it fell an equal distance from 

 a window-sill upon a broad granite step. On looking out. it could 

 not be seen ; closer inspection revealed a single spot of blood, and, 

 at the foot of the steps, a hole into which, presumably, it had 

 crept, and from which, four days later, it was coaxed, a little wild 

 but apparently uninjured. These two survivals are notable in 



view of the peculiarly solid and " chunky " form of the aninaal, 

 and the improbability that such accidents should occur in a wild 

 state. By allowing it to fall into water or upon soft material it is 

 intended to observe the attitude during descent. The sense of 

 distance may be cultivated. The brains of prairie-dogs will be 

 compared with those of squirrels. 



The subject of this note is 30 centimetres (13 inches) long, the 

 tail contributing 6 centimetres; it is fat, and weighs 755 grams 

 (26.6 ounces); the writer does not know the ordinary size and 

 weight. It is friendly to all, but recognizes familiar voices and 

 hands ; is practically omnivorous, drinks milk, and has killed and 

 devoured a ruffed grouse. Like all of the species, to a sudden 

 sound, the fall of an object, a rap on the door, the voice, a cough, 

 and particularly a sneeze, it responds by erecting the body and 

 barking. The nervous mechanism involved seems to be largely 

 reflex, rapidly exhausted, but nearly or quite uncontrollable; in- 

 deed, there is reason to believe that the second fall was due to an 

 unguarded erection of the body at the edge of the window-sill ; the 

 bark was heard at the striking of a large clock in the same tower, 

 and when the occupant of the room turned the dog had disap- 

 peared. Do any other animals display this reflex responsiveness 

 to sounds ? 



As a slight contribution to the mechanism of dreams it may be 

 added that the second fall and disappearance occurred during tl\^e 

 writer's absence ; that he is much attached to the prairie-dog, and 

 promptly sent directions to search for it, urging that the steps 

 should be removed if necessary ; and that the following night he 

 dreamed of superintending the demolition of McGraw Hall; 

 finally that neither to him nor to any others connected with 

 the university did their appear any incongruity in the destruction 

 of a fifty-thousand-dollar stone building for the recovery of a 

 prairie-dog. BtJRT G. Wilder, M.D. 



Ithaca, N.Y., Aug. 16. 



Ballooning of Spiders. 



McCook's great work on "American Spiders," whilst properly 

 rejecting some proposed explanations of their aeronautics, does 

 not offer any better explanation, but merely speaks of ascending 

 air- currents, and gives important observations which show that 

 the point of departure is an exposed rail fence or other elevated 

 place in sunshine. I would suggest that the explanation is to be 

 found in the fact that sunshine on such departure-platforms 

 causes an upward current by heating and rarifying the air, and 

 so starts the flight; and when (often after several vain attempts) the 

 gossamer-line is at length sent aloft, the sunshine on the line litself 

 will warm and rarify the surrounding lamina of air, and so in- 

 crease the ascending current as to carry upwards both the filament 

 and the suspended spider. For this last point I am indebted to 

 Professor C. S. Young. 



If these suggestions be good, then the interesting aeronautics 

 may be expected to occur only during sunshine, and the term 

 " ballooning " will not be entirely metaphorical, save in the sense 

 that the rarified gas is outside instead of inside the silk mechan- 

 ism. F. Macloskie. 



Princeton College, N.J., Aug. 18. 



AMONG THE PUBLISHERS. 



The index for the September number of the Chautauquan 

 shows the following inviting subjects : ' ' On the Nature and Value 

 of Folk Lore," by L.J.Vance; "Sacred Trees," by Dr. Ferd. 

 Adalb. Junker von Langegg ; " The Supreme Court of the United 

 States," by Eugene L. Didier; •' Experiment Stations: What is an 

 Investigation?" by Byron D. Ealsted, Sc.D. ; and " Modern Magic 

 and its Explanation,'' by Marcus Benjamin, Ph.D. 



— E. & F. N. Spon announce a treatise on ' ' Water Supply, 

 Drainage, and Sanitary Appliances of Residences," including 

 lifting machinery, and lighting and cooking apparatus, by Fred- 

 erick Colyer; "Sewage Disposal," being fourteen years' experi- 

 ence in works of intermittent downward filtration, separately and 

 in combination with surface irrigation, with notes on the practice 

 and results of sewage farming, by J. Bailey Denton (second eui- 



