June 1 6, 1887] 



NATURE 



153 



wind of 80 miles an hour at an elevation of 100,000 feet (less 

 than the height deduced by Verbeek for that reached by some of 

 the ejecta) might theoretically co-exist with a trade wind of 

 ordinary velocity at the earth's surface. 



It is not so much with reference to the velocity as to the 



■ lirection of the upper currents near the equator that Mr. 



Abercromby's itinerary observations are valuable, since they 



correspond both normally and exceptionally with what might be 



exj^ected from the laws of aero-dynamics. Theory is naturally 



perhaps, though still somewhat singularly, silent as to what is 



supposed to be the motion of the air in the upper regions of the 



belt bounded by 15° on either side of the equator. Ferrel's 



equations are not very satisfactory for this space, owing to the 



sinallness of the term zvw%m.Q representing the deflecting force 



'f terrestrial rotation {ablcnhingskraft), and close to the equator 



il altogether at the surface. That the wind there, however, 



ill maintains its westward component under the normal con- 



! lions which accompany the north and south trades is plain both 



>m Mr. Abercromby's and other observations. Higher up, 



Aing to the absence of friction, the air tends to move in the 



inertia curve " corresponding to its motion at the surface, whose 



radius of curvature is ■ ; — ; and since near the equator 



2ft) sm Q ^ 



sin is very small this curve is very nearly a straight line 

 parallel to the equator. Whatever therefore happens to the 

 surface wind through local influences such as latitudinal shift of 

 thermal equator or doldrums, or the establishment of a local heat 

 maximum on a land surface causing a deflection of the normal 

 trade wind into a local monsoon, ought not to interfere sensibly 

 with the general tendency of the upper air to stream from east to 

 west for a considerable space on either side of the equator. I 

 may just remark, en passant, that the belt bounded by 15° N. 

 and .S. latitude embraces an area of more than one- quarter of 

 the entire surface of the globe. 



The apparent anomalies as well as rules exhibited by Mr. 

 Ahercromby are thus seen to be in complete accordance with the 

 above principle. It is only when we get some distance away 

 from the equator that the gradient towards the poles in the 

 upper atmosphere becomes large enough to change the west- 

 ward into an eastward motion. As the air slides down this 

 slope the radius of the "inertia curve" becomes smaller, and it 

 veers through S.E. and S. to S.W., the normal direction of the 

 upper current at the boundaries of the trade zones. 



That the barometer gradient at a height of 13,000 feet over 

 the equator is very small either from or towards the poles may 

 be gathered from the following extract fro.n a table given by 

 Dr. .Sprung in his "Lehrbuch der Meteorologie " (Hamburg, 



r 



h^st Above 



Lat. 20" N. 

 10° 

 o 



10° S. 

 20° 



Height 13,123 feet. 

 Mean pressure in inches. 

 18*504 

 18-532 

 18543 

 18-547 

 18-547 



Above this height the gradient towards the poles would 

 increase, but theoretically there might be no change in the 

 direction of the wind near the equator. 



J"ne 3. E. Douglas Archibald. 



Mammaliferous Gravel at EUoughton, in the Humber 

 Valley. 



I WAS informed a short time ago that a large bone had been 

 found in a gravel-pit near Brough, on the Humber, and went at 

 once to examine the place. I found the "bone " to be a mam- 

 moth's tusk of large size, and learnt that other teeth and bones 

 had not infrequently been exhumed in the pit. As this seems 

 to be a new locality for mammalian remains, I think a short 

 description of the deposit may be found useful. 



The excavation was commenced about twelve months ago on 

 the top of a small isolated hill known as Mill Hill, which rises 

 out of the Humber Flat to a height of about 90 feet, close to 

 the village of EUoughton, and since that time there has been a 

 const mt and steady removal of the material, so that a good 

 section is now exposed. The hill forms an outlier of the Wold 

 Range, from which it is separated by low ground nearly a mile 

 in width, the north shore of the Humber lying about one mile 



to the south of it. It is composed of Oolitic rocks overlain by 

 gravel. The section at present shown is as follows : — 



A. Top-soil, &c.. 



B. Rough stony gravel, 

 with sand 



C. Yellow sand, 

 stony layers 



D. Hard gray 

 floor of pit 



with 



2\ feet. 



about 

 9 feet. 



about 

 5 feet. 



clay, forming! 



A British burial found in this 

 layer, on the west side of 

 the pit. 



Contains pebbles of flint, sand- 

 stone, red chalk, Oolitic 

 limestone, and other local 

 rocks, along with a few 

 well-worn erratic pebbles of 

 felstone, quartzite, &c. ; also 

 rolled lumps of clay and 

 streaks of carbonaceous mat- 

 ter like decayed vegetation. 



The mammoth's tusk and 

 other bones were found in 

 this bed. 



Of doubtful age, but probably 

 , belonging to the Estuarine 

 [ Oolites. 



In the rough gravel, B, there are some boulders of local rocks 

 so large as to suggest the idea that floating ice has been the 

 agent of their transportation, especially as it seems as though the 

 blocks must either have been raised from a lower level, or floated 

 over the depression intervening between this hill and the Oolitic 

 exposures in the flanks of the adjacent Wolds. 



The junction of B with C is very well marked, and there are 

 signs of erosion, and unconformity between them ; but as the 

 whole of the beds are current-bedded and irregular, this line ol 

 separation may be of no importance. On the other hand, since 

 fossils seem only to be found in the sand, C, this may be the 

 remains of an older deposit which has been denuded during the 

 deposition of the overlying unfossiliferous gravel, B, and this 

 latter bed may be a continuation of similar rough unfossiliferous 

 gravels seen on the lower ground to the westward. 



If the clay exposed on the bottom of the pit really forms part 

 of the Oolites, I see no means of determining the age of these 

 gravels ; but my impression is that at any rate they are not older 

 than the oldest boulder-clay of Holderness, and are probably 

 j not later than the newest. At Hessle, six miles to the eastward, 

 bones have been found in a chalky rubble underlying boulder- 

 clay, which Prof. Phillips regarded as pre-Glacial. At Biel- 

 becks, seven miles to the northward, similar remains were 

 obtained in 1829 from a fresh- water deposit which I think was 

 regarded as post-Glacial. It may be that these deposits will 

 eventually prove all to be of one age. 



The size and condition of the tusk were such that I do not 

 think it can have been carried hither "by water-currents alone. 

 It has more probably either been dropped from the floating or 

 living carcase of the animal or from a mass of floe-ice. Its 

 length, as it lay exposed on the floor of the pit at the time of 

 my visit, was 90 inches, but the workmen said they had broken 

 up about two feet of the ' ' thick end " before they were aware ; 

 and as the apex was also blunted and badly preserved, I think 

 its length when first deposited cannot have fallen short of 10 

 feet. Its diameter was 6 inches at a distance of 10 inches from 

 the apex ; 7J inches at 20 inches ; 8 inches at 30 ; 8J at 40, 

 beyond which it did not seem perceptibly to thicken. It lay in 

 a water-logged gravel, and was in a very friable state ; and 

 though I was enabled, through the kindness of Mr. H. Lyon, 

 the owner of the pit, to strengthen the specimen with cement, it 

 crumbled into small splinters when an attempt was made to 

 remove it, and was irretrievably ruined. Its curvature was not 

 great, and would lie within a breadth of about 20 inches. 



The only other remains I have yet obtained from the pit are 

 some portions of the teeth of the mammoth and a few irrecogniz- 

 able fragments of bone. 



In the top-soil on the west side of the pit a British burial has 

 been cut through, wherein lay the bones of a human skeleton, 

 together with a fragmentary vase with the characteristic 

 ornamentation. G. W. Lamplugh. 



Bridlington Quay, June 6. 



Fall of Peculiar Hailstones in Kingston, Jamaica. 



Shortly after midday on the 2nd inst. a thunderstorm 

 visited this city ; the rain began with the wind from the east, 

 as is usual with our May seasons, but it speedily changed to the 



