540 



NA TURE 



October 7, 1897 



of sinking through watery strata, (6, 7, and 8) methods 

 of supporting excavations and the construction of dams, 

 (9, 10, and 11) methods of working, and (12) pumps and 

 ore dressing. The illustrations have been selected with 

 great care fron) standard authorities, due acknowledg- 

 ment of the source being made in each case. The only 

 fault that can be found with the diagrams is, that the 

 authors have covered so wide a field that it has been 

 necessary in some cases for them to crowd together into 

 one diagram too many drawings. The best of the series 

 are the remarkably bold and effective diagrams illus- 

 trating methods of working. The least satisfactory are 

 the perspective views of machinery and of timbering. 

 Plans and sections would have been better. 



In Northern Spain. By Hans Gadow, M.A., Ph.D., 

 F.R.S. Pp. xvi -f 421. With map and eighty-nine 

 illustrations. (London : Adam and Charles I31ack, 

 1897-) 

 The incidents and impressions of two prolonged journeys 

 through the northern and north-western provinces of 

 Spain are brightly recorded in the volume before us. 

 Personal experiences always have in them the making 

 of an interesting book ; and when things are seen with 

 an intellectual eye, and the itinerary refers to places off 

 the beaten track, the narrative is sure to engage atten- 

 tion. The present work, in which the wanderings of 

 Dr. Gadow and his wife are described, possesses both 

 these claims to recognition ; moreover, it is well illus- 

 trated by camera and pencil. The accounts of the 

 districts traversed, and the notes on the characteristics 

 and customs of the inhabitants, will interest geographers; 

 while archaeologists will find a chapter on the Dolmen 

 of Alava, and numerous short descriptions of other in- 

 teresting antiquities. For students of biological science 

 there are chapters on the fauna and flora of Northern 

 Spain. The former chapter is a valuable analysis of the 

 fauna of the Iberian peninsula. 



LETTERS TO THE KDITOR. 



'The Editor does not hold Jiiviself responsible for opinions ex- 

 pressed by his correspondents Neither can he undertake 

 to return^ or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 Mo notice is taken of anonymous communications.'] 



The Highest Kite Ascent. 



The general interest in scientific kite-flying leads me to send 

 the following account of a flight here on September 19, when 

 meteorological records were brought down from the greatest 

 height which it is believed a kite has yet attained. The experi- 

 ment was part of an investigation into the meteorological condi- 

 tions of the free air now in progress here, and wiiich is aided by a 

 grant from the Hodgkins Fund of the Smithsonian Institution. 



A Richard baro-thermohygro-graph (described in La Nature, 

 8 Fevrier, 1896), weighing but 3 lbs., was hung 130 feet below 

 two large Hargrave kites, and other kites were attached at in- 

 tervals to the four miles of steel wire forming the flying-line, the 

 total sustaining surface of the seven Hargrave kites used being 

 something over 200 square feet. At their highest position the 

 two topmost kites were 9386 feet above Blue Hill, or 10,016 feet 

 above sea-level. The altitudes, at short intervals of time, were 

 obtained from angular measurements with a theodolite, and were 

 confirmed by the barometer record of the meteorograph. 



This instrument left the ground about noon, and the greatest 

 height was reached soon after four o'clock, the meteorograph 

 remaining more than a mile above the hill during five hours. 

 A httle more than two hours were required for the steam-winch 

 to reel in the four miles of wire, and the meteorograph returned 

 to the ground at 6.40 p.m. The wind on the hill blew from 

 the south with a velocity of about twenty-five miles an hour, 

 but veered to the west in the upper air. The chief results, 

 obtained from the automatic records, which are smooth and 

 distinct, are these : — The temperature at the highest point was 



NO. 1458, VOL. 56] 



38°, while at the ground at the same time it was 63°, giving a 

 decrease of 1° per 375 feet rise, which is less than normah 

 The relative humidity at the ground was about 60 per cent, of 

 saturation, but rose rapidly with height to about 4000 feet, 

 which is the level of the cumulus clouds. It then fell, but rose 

 again to nearly saturation above 7000 feet, when approaching 

 the level of the alto-cumulus clouds. The humidity fell to less 

 than 20 per cent, at the highest point reached. Throughout 

 the flight the sky was clear. A. Lawrence Rotch. 



Blue Hill Meteorological Observatory, September 23. 



Outlying Clusters of the Perseids. 



The clearness of the sky, and the' absence of the moon's light 

 at the end of July and in the beginning of August last, were 

 unusually favourable conditions here for watching the progress 

 of the August meteor-shower of Perseids from the first signs of 

 its appearance up to very near its date of greatest brightness. 

 Having intended to observe the shower in connection with a 

 watch arranged by Mr. Denning to be kept on the Perseids' 

 this year at many places, and an early beginning of the watch 

 having l^een recommended, in order to note the progressive 

 changes of the radiant-point's position, I had little expectation 

 of being able to contribute much to this inquiry from the usual 

 scarcity of the Perseid meteors in the shower's early stages. 



A theory of its progressive motion had been formed and com- 

 pared with observations by the late Dr. Kleiber, of St. Peters- 

 burg (Monthly Notices of the Royal Astronofjiical .Society, vol. 

 lii. 1891-92, p. 341), depending for its application on certain 

 effects and laws of planetary perturbations. Starting from the 

 same, or from a very similar principle of the effects of planetary 

 disturbances on meteor-orbits with that used by Prof Adams to 

 calculate the motion of the node of the November meteor- 

 system, that without change of shape or of inclination to the 

 plane of the ecliptic, cTf the long elliptic orbits round the sun, 

 the line of nodes or intersection of the orbit-plane with the 

 ecliptic is carried secularly backwards or forwards slowly round 

 the ecliptic-circle, according as the motion of the meteors in the 

 orbit is direct or retrograde. Dr. Kleiber showed that the 

 meteors' apparent radiant-point on the earth's encountering the 

 stream, would also be carried with the orbit round the pole of 

 the ecliptic at the same rate in longitude, and without any 

 changes in its apparent latitude. If the earth should thus at any 

 point encounter meteors of the shower which have undergone 

 less or greater secular displacements of their nodes than the 

 main meteor-body, so as to furnish slender meteor streams 

 observable a few days before or after the principal shower-date, 

 since the earth advances round its orbit through nearly one 

 degree of longitude each day, the differences in longitude 

 between these slender streams' and the main stream's radiant- 

 points will evidently be as many degrees, or very nearly as many 

 degrees as the earth takes days to traverse the distances be- 

 tween the outlying meteor-systems and the main one. Tested 

 by this criterion. Dr. Kleiber showed that of forty-nine apparent 

 foci of the Perseids observed by Mr. Denning, in various years, 

 between July S and August 16, forty-six were reducible by 

 applying to all their longitudes the corrections corresponding 

 according to the theory with their dates, to within a circle of 

 only 2° radius round a point at 43°*6, -f 57°"i assigned by Dr. 

 Kleiber as the cometary radiant-point. This surprisingly close 

 agreement certainly afforded a convincing proof of the adequacy 

 of the perturbation theory to explain the recorded changes of 

 position of the Perseid meteors' radiant-point ; but I had been 

 rather sceptical of obtaining from such scanty materials for 

 observations as the very early traces of the Perseid comet 

 meteors seem to offer, positions of sufficient accuracy to be 

 capable of furnishing with much reliability such a very satis- 

 factory agreement ? In a watch of three hours, however, on the 

 exceedingly fine night of July 22 last, seven Perseids were 

 recorded here, of which two (like two on the i8th and 20th), 

 were directed nearly from the usual shower-centre at about 

 43°, + 57°, but the other five diverged so distinctly from about 

 23°, -1-49° near v and ^, at the point, instead of from near x and 

 rjat the handle of the sword of Perseus, that the displacement 

 of the radiant-point at this early date from its usual position to 

 one in, at least, considerably lower right-ascension and declina- 

 tion, was at once very evident, and I was induced to longer 

 watches, on later nights, by this first indication, than I would 

 have thought likely, otherwise to be very usefully productive. 

 The following short Table (I.) gives a summary of the 



