NATURE 



[Al'RIL 



1909 



tion in the region under discussion is about 20° C. in 

 14 kilometres. Usually it is much less. In the lower part 

 of the atmosphere the variation is generally 60° C. to 70° C. 

 in 10 km. The upper region is therefore comparatively 

 isothermal. The rapid increase of temperature between 

 12 km. and 13 km. in the Uccle ascent of July 25, 1907, 

 is an example of a phenomenon which occurs in the lower 

 layer of the isothermal region in about one-third of the 

 ascents. E. Gold. 



Vienna, April 7. 



The Greenwich Winter of 1908-9. 

 If the art of long-range forecasting is ever acquired, it 

 will probably be through a careful study of past experi- 

 ence (of which we have now nearly seventy years' excellent 

 data for Greenwich), including, among other things, what 

 are known as "sequences," cycles (if any), and the rela- 

 tion of weather to solar, and possibly lunar, changes. 



I propose to offer a few remarks on the state of avail- 

 able knowledge regarding winter, at the end of last 

 autumn, and year, and its bearing on what followed. 



By the end of November we had had only three frost 

 days. After such autumns as the last, with all three 

 months dry, December (as was pointed out in a table) has 

 nearly always been mild (twelve cases out of thirteen). 

 Thus it was pretty clear that the second half of 1908 would 

 have less than the average of frost days (18). The actual 

 number is 8. 



The same table seemed to point to at least two of the 

 three winter months being mild ; and that is what 

 happened, though, of course, with the cold of February 

 the winter (proper) was slightly severe as to mean tempera- 

 ture and number of frost days (the latter 36, which is 4-3). 

 When the second half of a year has less than the 

 average of frost days (18), the total, from September to 

 May, is generally also under average (54). There are 

 only three exceptions (1857-8, 1891-2, 1894-5) i" ^ tot^' 

 of thirty-one cases. Thus it would be reasonable to expect 

 that the total for the first half of 1909 would not be more 

 than 46 (i.e. 54 — 8). There have been 42 up to the end 

 of March, and it is possible the total may be a little 

 in excess, conforming to the " exception " instead of the 

 rule " (a contingency which has often to be regarded). 

 The number up to April 20 is 46. 



If we indicate by a plus or minus sign the character 

 (as regards frost days) of each winter (December-February) 

 ending in a sun-spot maximiiin year, and the four winters 

 following, we have the following table : — ■ 



Max-, year Max. i = 3 4 



1848 ... + ... - ... + ... - ... - 

 i860 ... + ... 4- ... - ... ... -f 



1870 ... -1- ... + ... - ... - ... + 

 1883 ... - ... - ... - ... 4- ... + 

 1893 ... + ... - ... + ... - ... - 

 I90S ... - ... - ... + ... - ... 



We might here note (without pressing the point too 

 much) that each of the first five groups has at least two 

 plus values, and as the four winters 1905-8 show only one, 

 a plus in the vacant place seemed the more likely. 

 Further, one might show that the average for the first 

 four vertical columns is a minus value; for the fifth, a 

 plus. The winter, as stated, had an excess of three frost 

 days. 



Another point of view. We might fairly expect the 

 next sun-spot minimum in 1912 (the series before is 1843, 

 1856, 1867, 1878, 1S89, 1901). Then this year would be 

 the third before. Consider how many frost days there 

 were in the first half of the third year before previous 

 tninima. We find : — 



F.r). Relation to average 



i8i;3 

 1864 



1 886 

 1898 



? 

 -f 6 



-15 



Av. 40 +4 



This points to a probable excess. The number to March 31 

 is 42. 



.'\fter a very dry autumn the winter tends to be dry. 

 Thus of the ten driest autumns, nine were so followed. 

 The winter (December-February) was a very dry one. 



I submit, then, that, on the threshold of last winter, 

 there was reason to expect (i) December to be mild, and 

 frost days in the second half of igo8 under average (18); 

 (2) at least two mild months in winter (December- 

 February) ; (3) frost days in first half of 1909 not more 

 than 46, but (4) over average (36) ; (5) frost days in winter, 

 over average (33) ; (6) a dry winter. 



While most of the above facts were, I think, known to 

 me at the outset, I quite agree that it is one thing to 

 make a retrospective comparison like this, and another 

 thing to predict successfully. Of many pieces of evidence, 

 some may seem in conflict, and one has to try and judge 

 which is the more weighty and trustworthy. I may further 

 admit that the cold this year has a little exceeded what I 

 looked for. 



It may be useful, nevertheless, to direct attention to 

 tliese comparisons, emphasising the fact that there is a 

 large body of evidence (as I believe) in relation to the 

 character of a coming season. It seems to have been too 

 readily assumed, hitherto, that we have absolutely no light 

 on the subject, and that any one venturing an opinion on 

 an approaching season is, by that fact, declared a dreamer 

 or a charlatan, his " hits " and his " misses " being alike 

 mere chance. 



That the winter season of 1908-9 would at least not be 

 a very severe one (say, more than sixty frost days in 

 September-May) I consider to have been provable by a 

 strong consensus of facts. 



.'\lex. B. M.acDow.ill. 



Fluorescence of Lignum Nephnticum. 



With reference to Mr. Benham's letter in Nature of 

 .'\pril 8 (p. 159), the following statements may be of 

 interest. 



The wood known as Lignum Nephriticum reached Spain 

 probably about or before the middle of the sixteenth 

 century. Monardes (1574) and Fr. Hernandez (about the 

 same time) were familiar with the fact that a watery 

 infusion of the wood in a short time assumes a blue 

 colour, but they do not mention the peculiar dichroism of 

 the infusion. This was described for the first time by 

 Athanasius Kircher in his " Ars Magna Lucis et Umbrae " 

 (1646), and. apparently independently of him, by Joh. 

 Bauhin in his " Historia Plantarum Universalis " (1650). 



The origin of the wood has so far remained obscure. 

 Linn^us — and already Plukenet and Dale before him — re- 

 ferred it to Moringa pterygosperma^ the horse-radish tree 

 of India, but without reason, as was pointed out long 

 ago. Researches, however, made at Kew within the last 

 few weeks have convinced me that Lignum Nephriticum 

 is the wood of Eysenhardtia amorphoides, H.B.K., a 

 small Mexican tree or shrub of the order Leguminosje. 

 The blue inflorescence exhibited by an infusion of the wood 

 of this tree is very brilliant indeed. O. Staff. 



Royal Botanic Gardens, Kew, April 16. 



In 



Morphology of the Enteropneusta. 



paper " On the Morphology of the Excretory 



Organs of Mctazoa : a Critical Review," recently pub- 

 lished in the Proceedings of the American Philosophical 

 Society (vol. xlvii., 1908), the author. Dr. T. H. Mont- 

 gomery, slates on p. 577, with reference to the Entero- 

 pneusta, that in Spengelia I described rudimentary pores 

 along the whole trunk in 1899. What I did describe in 

 this connection was a single pair of structures which I 

 thought might represent a single pair of truncal canals 

 and pores. 



Dr. Montgomery says that he had not seen the original 

 description, and consequently was unable to add further 

 details. The work (" Zoological Results ") can be 

 obtained at an easy cost from the Cambridge University 

 Press. Perhaps, however, the original description is not 

 deemed worthy of perusal, although it would be charitable 

 to assume that, like the proverbial egg, it must be good 

 in parts. Arthur Willev. 



Colombo, Ceylon, March 22. 



NO. 2060, VOL. 80] 



1 



