6o 



NA TURE 



{Nov. 2 1, 1889 



although quite independent of natural selection, is in no way 

 opposed to natural selection, and may therefore be regarded as a 

 factor supplementary to natural selection." This passage occurs 

 in the most conspicuous part of the paper, viz. at the close of 

 the introduction. In the next most conspicuous part — viz., 

 at the close of the paper itself — it is said, " Without natural 

 selection, physiological selection would be powerless to create 

 any differences of specific type, other than those of mutual sterility, 

 and trivial details of structure, form, and colour." 



So much for distinct professions. But as I am tired of contro- 

 verting the statement that I both intended and perpetrated an 

 "attack " on Mr. Darwin's theory, I will not now burden your 

 columns by supplying the context, or otherwise easily explain- 

 ing the passages Ivhich Prof. Lankester quotes in support of 

 this statement. On a future occasion, however, I hupe to avail 

 myself of a mor- fitting opportunity fully to display the relation 

 in which my "laborious essay" stands to the work of Mr. 

 Darwin ; and then I trust it will be clearly seen that, whatever 

 we may severally think about the "complementary principle " of 

 physiological selection, at all events it is in no way hostile to 

 the cardinal principle of natural selection. 



Edinburgh, November 19. George J. Romanes. 



How not to Teach Geometry. 



As I have come across an almost unforeseen development of the 

 above heading, I take the liberty of bringing it before your 

 readers. For myself, I may state that I have considered the 

 " learn a proposition off by heart " method was sufficiently bad, 

 but what is to be made of the method described in the following 

 extract from a note which I recently received from my friend : — 

 " We have half of a proposition written on the board, and then 

 we write it at home from memory ; then the other half is 

 written on the board, and we write that at home from 

 memory. Then we have to learn the whole proposition at once, 

 to be able to write or say it with different letters. We are not 

 allowed to have a printed Euclid book — we are only allowed to 

 have a book of Enunciations." 



Of course this refers to Euc. i. i. 



I beg to commend the above extract to the Association for 

 the Improvement of Geometrical Teaching. I do not know 

 whether to add the name of the school where the above system 

 is followed by one of the teachers. 



Herbert J. Woodall. 



Normal School of Science, South Kensington, 

 November 11. 



P. S. — I should like to see opinions on the teaching described. 



A Brilliant Meteor. 



Is not the meteor seen from Warwick School on November 4 

 the same as that mentioned in the following from my daughter, 

 written from the school at Brookfield, Wigton, Cumberland? 



"On Monday night (November 4), at 7.55 p.m., when out 

 on the playground viewing the stars, I saw a most beautiful 

 meteor. It seemed to be very near, and was in sight for quite a 

 long time. It appeared just over Skiddaw — that is to say, due 

 south — and went towards the south-east. It had a long tail of 

 light, and burst, and sent out beautiful colours, and disappeared 

 near the horizon." 



I may add that, last Sunday, November 10, at about 5.56 

 p.m., I saw here a very bright meteor pass from a point perhaps 

 south-south-west, and altitude about 25°, to a point perhaps south 

 by east, and altitude about 10° or 12°. It was lirighter than 

 Venus when the planet is at its brightest, I think ; and it seemed 

 to flash out still more brightly just before disappearing ; but the 

 colour did not change perceptibly from its former soft white 

 light, and there was no appearance of bursting. At the time of 

 disappearance, its train of light must have extended over several 

 degrees. Wm. Scarnell Lean. 



Ack worth, November 16. 



THE CAUSES AND CHARACTER OF HAZE. 



T T NLIKE fog, haze commonly occurs in this country 

 ^ when the lower air is in a state of unusual dryness. 

 It is not only a frequent accompaniment of a spell of fine 

 dry weather, but may be, when in combination with certain 



other conditions, a sign of its approach. Night or morn- 

 ing fogs, and in winter persistent fogs, often signify a calm 

 and settled condition of the air and the prevalence of fair 

 weather. Heavy dews, especially in the autumn, likewise 

 portend fine weather, but usually of shorter duration. 

 Fogs appear usually in one of two conditions : either the 

 air is nearly saturated up to a considerable height, or else 

 is unusually dry, except in a stratum immediately above 

 the ground. In the first case, radiation or condensation 

 from some cause produces, by a slight lowering of 

 temperature, a large precipitation of vapour ; and in the 

 second case, radiation from the earth's surface being 

 excessive, owing to the diathermancy of the dry atmo- 

 sphere, the stratum next the ground rapidly reaches its 

 dew-point, fog is formed, and this fog continues to radiate 

 to the clear sky and further to reduce temperature. Haze, 

 on the other hand, appears often in weather distinguished 

 by unusual dryness, on the surface as well as at a con- 

 siderable altitude above the ground. The air remains for 

 many days uniformly dry, the nights being nearly dew- 

 less, and the sky often free from clouds. The chief differ- 

 ence to be observed, then, is this, that fog requires 

 saturation where it occurs, while haze seems to be 

 favoured rather by a dry atmosphere. 



Haze does not prevail on the continent of Europe or in 

 the interior of North America to anything like the same 

 extent as in England ; nor, probably, in mid-ocean to the 

 same extent asneartheshoresof northern countries. On the 

 east coast of Scotland, and, indeed, overall North Britain, 

 it is exceedingly common, especially in the spring, and 

 during the prevalence of east wind, although with west 

 winds the atmosphere is frequently clearer in summer 

 than in Southern England. Over Southern England it is 

 a common accompaniment of winds between east-south- 

 east and north-east inclusive. It appears to prevail more 

 on the eastern than on the western coasts when east 

 winds are blowing. In Western Surrey, when the lower 

 air moves from a westerly direction or is calm, the ap- 

 proach of east wind is announced by a light haze obscur- 

 ing distant views, before the east wind has actually 

 arrived on the spot of observation. This is not in all 

 cases due to the descent of London smoke from a higher 

 stratum, where the east wind first gains ascendancy, for the 

 phenomenon maybe observed in other localities. The haze 

 produced on the first arrival of the east wind is thicker than 

 that which remains when the east wind has gained a strong 

 hold, and the neutral band where calm prevails between 

 a south-west and a north-east current is marked by the 

 thickest mist. In winter a dark fog frequently marks this 

 neutral zone, often not more than one or two miles in 

 breadth, and the zone moves eastwards or westwards 

 according as the west or east wind exercises the strongest 

 pressure. I have frequently observed this phenomenon 

 with great distinctness. In winter, the approach of the 

 equatorial after the prevalence of the polar current is 

 often betokened by a damp fog and the contrary change by 

 a dry fog ; the same changes in summer are respectively 

 marked by a great increase of transparency and by a 

 spreading haze or mist. The following observations taken 

 in Scotland illustrate the phenomena accompanying a 

 change from west to east in August. St. Fillan's Hill is 

 a small, steep, isolated volcanic cone about 300 feet in 

 height, standing in the middle of the valley of the Earn, 

 about two miles from the lower end of Loch Earn, in 

 Perthshire. The air was clear, and a fresh westerly 

 breeze was blowing when I was on the summit, about 5 

 p m. The breeze suddenly began to slacken, and in about 

 five minutes had dropped altogether. Then down the 

 valley eastwards a blue haze began swiftly to climb the 

 glens tributary to Stralhearn, and the whole air eastwards 

 grew obscure. The calm only lasted a little more than 

 two minutes, and then suddenly a strong wind from the 

 east set in, and soon the air, westwards as well as east- 

 wards, was robbed of its transparency. The east wind 



