58 



SCIENCE. 



[Vol. XVIII. No. 443 



ing their position, point to very complicated conditions of 

 movement. But the counter-influence of "Himmelsluft," 

 as compared with the movement of the earth round the sun, 

 is a necessary consequence, not only of the movements in - 

 the hig-hest strata of the atmosphere, but also of the effects 

 of pressure, which could not remain unnoticed in the case 

 of very delicate barometrical measurements. If the daily 

 period of fluctuation of the atmospheric pressure were not 

 influenced by so many difl'erent factors, — for example, by 

 the daily warm period and, theoretically at least, by a cer- 

 tain operation of ebb and flow caused by the sun and the 

 moon through their powers of attraction in the atmosphere 

 as well as in the ocean, and perhaps also by the electrical 

 conditions of the atmosphere, — there must be, at that time 

 of day at which a given station arrives, in consequence of 

 the earth's rotation, on the front side of the mighty "vessel" 

 which transports us round the sun with a velocity of nine- 

 teen miles a second, a somewhat greater atmospheric press- 

 ure. This time ot day is, as a rule, between midnight and 

 midday. 



In the polar regions the state of affairs is a little more 

 complicated. In these zones an observer can, during the 

 winter, for a longer or shorter period, according to the geo- 

 graphical latitudes, remain on the front side of the earth, 

 while in summer he finds himself turned over on to the hack 

 of the earth, viz., on that side which is away from the direc- 

 tion of movement. In lower latitudes the mercury in the 

 barometer must always stand higher during the morning 

 hours than during the rest of the day. In consequence of 

 the collective effect of the various factors which influence 

 the daily period of the pressure of the atmosphere, the result 

 is a very complicated one. 



Within the last five or six years a group of phenomena 

 has arisen, which is of the greatest importance in considering 

 the problem of the conditions in the upper strata of the at- 

 mosphere. The last of the series of phenomena connected 

 with the Krakatoa eruption are the so-called luminous clouds, 

 which have since that time been observed during the night 

 in the summer months on both hemispheres at a height of 

 about fifty miles. These clouds consist obviously of the 

 smallest molecules of water, which have been projected to 

 their highest point, and which during the summer nights 

 have reflected down upon us from that great height the di- 

 a-ect rays of the sun. The long duration of this phenomenon 

 imakes it a very remarkable one. During the last two years, 

 lor which very accurate photographic determinations of alti- 

 tude are available, the average height of these clouds has not 

 altered. This can only be explained if we suppose tlie exist- 

 ence in those altitudes of an opposing force, which nearly 

 overcomes the influence of gravity, in consequence of the 

 giving off of electricity. 



In the last few years not only has the density of this col- 

 lection of matter been very materially lessened, but its geo- 

 graphical and periodical distribution over the different re- 

 gions of the globe has become more restricted and regular. 

 In Germany these clouds have, during the last three years, 

 only been seen between the end of May and the end of July, 

 towards the north, at a distance of from 310 to 435 miles ; 

 on the southern hemisphere, at the southern extremity of 

 America, only during the local summer (December), and 

 then towards the south. It may, therefore, be supposed that 

 this collection of the smallest molecules travels every year 

 from one polar zone of the earth to the other, so that it is 

 found just over that hemisphere where summer is at its 

 heiffVit. This periodical movement would be completely un- 



intelligible if the counter-influence of the "'Himmelsluft" 

 on those high strata of the atmosphere which participate 

 more or less entirely in the rotation of the earth on its axis 

 and round the sun, did not furnish an explanation. In con- 

 sequence of the inclined position of the earth's axis, and of 

 the counter-effect of the "Himmelsluft," there occurs from 

 June to December a disposition, reaching its maximum in 

 September, on the part of those strata, to travel from the 

 northern to the southern hemisphere; while from December 

 to June the reverse is the case. It is calculated that for such 

 a periodical journey from pole to pole an average velocity in 

 the north and south direction, or vice versa, of only little 

 more than a yard a minute is necessary, a rate which is quite 

 insignificant when compared with the velocity of nineteen 

 miles a second, with which the relatively quiet "Himmel- 

 sluft " operates on the upper strata of the atmosphere which 

 move with the earth. 



Extensive investigations and measurements are still needed 

 in order to arrive at a result in this matter, and it is only 

 by means of the fullest co-operation of numerous observers 

 in all parts of the world that the necessary data for this pur- 

 pose will be obtained. 



MILK FROM TUBERCULOUS COWS. 



According to a report by United States Consul Ryder of 

 Copenhagen experiments have been resumed in Denmark 

 towards elucidating the question whether milk from tuber- 

 cular diseased cows, even in such cases where the udder was 

 not afl'ected with tuberculosis, can be the means of communi- 

 cating infection. In these experiments the investigation 

 was made in all with the milk from twenty-one diseased 

 cows, with which forty guinea-pigs were inoculated. It had 

 been intended that two guinea-pigs should be inoculated from 

 each sample; but in two cases, owing to the number of these 

 animals having fallen short, only one guinea-pig could be 

 employed, from two to three cubic centimetres of milk being 

 used on each occasion. The milk samples were taken by the 

 veterinary surgeon of the cattle market, the cows being 

 milked by him and the milk caught up into small bottles. 

 The veterinarian selected only such cows as, on examination 

 during life, could be classed by him as suffering in a high 

 degree from tuberculosis ; and in every case the udder and 

 chest intestines of the animals were afterwards sent for ex- 

 amination, so as to obtain full assurance of the correctness 

 of the diagnosis, as well as to ascertain the extent of devel- 

 opment of the disease. The inoculated guinea-pigs were kept 

 in isolated cages in such manner that only the two which 

 had received milk from the same cow came into contact with 

 each other. Three of the guinea-pigs were killed by rats, 

 fortunately, however, at such distance of time (24 or 35 days) 

 after inoculation that the inoculated tuberculosis must have 

 shown itself had it been present. Two others died of casual 

 (not tuberculous) lung disease after the lapse of a month 

 and a half and two months, having no sign whatever of 

 tuberculosis. 



The results obtained from these inoculations are that milk 

 from seventeen of the examined cows had no influence in 

 producing tuberculosis in the guinea-pigs, while the milk 

 from four of the cows showed itself to be communicative of 

 infection; but in three of these cases, on examination of the 

 udder most minutely, this could scarcely be considered in a 

 perfectly sound state. In the one case two small tumors 

 were found of about the size of a pea; in the two others, of 

 the size of a hazel-nut; but in all the cases, with a slight 



