June 22, 1893] 



NA TURE 



175 



Now, turning to Mr. Dixon's letter (p. 149), it does not seem 

 to me that he is perfectly candid. He accuses me in his con- 

 cluding paragraph of an unfair practice by omitting the word 

 "direct," but no such word occurred in his letter on p. 103, to 

 which I was replying ; nor is what he now says consistent 

 with the surface meaning and intention of the second paragraph 

 in his former epistle, so far as I can judge. A withdrawal of 

 that hasty and misleading paragraph is what I had expected from 

 him. 



In the first paragraph to his recent letter he explains why he 

 considers that the fact that potential energy belongs to a system is 

 hostile to the idea of identity, but his proof does not appear to 

 me valid unless the phrases "belongs to " and " has no local 

 habitation within" are considered identical. If he can show 

 that a given portion of potential energy "has no local habita- 

 tion within a system," he will undoubtedly be usefully attacking 

 the proposition that it possesses identity, but I do not see that 

 he has even attempted such a proof at present. 



Oliver Lodge. 



Popular Botany. 



I VISITED Tyne Dock yesterday, in order to attempt to solve 

 the question put by Mr. A. \V. Bennett in your issue of the ist 

 inst. 



The plants which caused the fatality grow in a small hollow 

 close to a newly-opened road. The surviving child is but 

 five years old, and therefore much too young for any evidence of 

 hers to be convincing. 



There seems little doubt, however, that the hemlock, Conium 

 maculatiim, brought about the death of the other two children. 

 Large quantities of this, looking very attractive just now, are 

 growing on the spot, together with smaller quantities of 

 HeracUum sphondylinm, Anthriscus sylvesti-is, and a very 

 few plants of Bunium fiexuosum at the margin of the hollow. 

 No other umbelliferous plant is growing near. Yesterday, 

 troops of children were gathering the young and pretty leaves of 

 the hemlock, and making them up into bouquets with grasses 

 and flowers. 



The children, who died from the effects of eating the plant 

 were aged respectively four and five years, and probably, in 

 common with thousands of others in the district, would not 

 recognise cabbage if they saw it growing, which very likely they 

 never did. I have met many very much older children here 

 who are as ignorant of common garden and field plants. 



Gatesheadon-Tyne, June 12. John Bidgood. 



The Big and Little Monsoons of Ceylon. 



It is well known to all Anglo-Indians, even the least scien- 

 tific, that the summer monsoon is ushered in by two periods 

 of rain-burst, called respectively the chota and burra barsat. 

 The former occurs sometimes in April or May, and the latter in 

 June or July, the precise dates varying not only with the 

 locality but with the year. The chota barsat only lasts a few 

 days, and is looked upon as the advance guard of the burra 

 barsat, or great rains. 



The conditions which tend to produce the chota barsat have 

 not, so far as I am av/are, been studied in detail, but are prob- 

 ably similar in character though on a smaller scale, and more 

 local than those which regulate the inception of the burst of the 

 monsoon, as it is popularly termed. It can be readily under- 

 stood that as soon as the solar rays are sufficiently powerful to 

 heat up a portion of the land area, and by lowering the pressure 

 todetermine an inrush of surrounding marine air, condensation 

 and precipitation will occur much in the same way as in the 

 burra barsat when the air over the whole peninsula has become 

 heated, and the saturated air from the equatorial Indian Ocean 

 rushes in in a large and continuous stream towards the low 

 pressure area thus formed. In the former case the conditions 

 are not only more local and ephemeral owing to the small 

 amount of vapour formed over a comparatively cool sea, but 

 aremixed up with the residue of the cold weather disturbances, 

 which are due to anti-monsoon conditions. 



Mr. Blanford, in his admirable monograph on the rainfall of 

 India, has compared the direct solar action which sets the mon- 

 soon in action to the pull of the trigger, by which the intrinsic 

 latent energy of the resulting air-stream is shot forth. In the 

 case of the chota barsat the comparison holds equally good 

 only the resulting charge is feebler. 



NO. 1234, VOL. 48] 



Now it has been recently maintatned that while the distribu- 

 tion of temperature anomalies in the Indian peninsula regulates 

 the inception of the little monsoon and its accompanying chota 

 barsat, it is only when the central Asian plateaux become 

 warmed up so as to produce an inflow beyond the Himalayan 

 barrier, which must consequently affect the upper as well as 

 the lower atmospheric strata, that any general deep movement 

 of the equatorial vapour-laden air occurs on a scale sufficient to 

 produce general monsoon rains. That in fact there are two 

 movements, one in the lower air, and the other in the air above 

 the first 5000 or 6000 feet, and that it is only when the two 

 occur coincidently that we get the grander phenomena which 

 accompany the burst of the big monsoon, as they term it in 

 Ceylon. Some such theory appears necessary to account, not 

 merely for the peculiar suddenness of the burst, but also for its 

 variable date of arrival in different years. Until, however, 

 we know more of the meteorological conditions of Central Asia 

 and Thibet, this hypothesis must remain in a tentative state. 

 Meanwhile, however, it is undoubtedly valuable to find that 

 these two periods of rain-burst are not only distinct enough to 

 be referred to under separate names over a large part of India, 

 but in Ceylon are considered so important as to have their dates 

 separately recorded by the Marine Master attendant at Colombo. 

 In the excellent Ceylon Mercantile and Planting Directory, 

 edited by the late Mr. A. M. Ferguson, and now carried on by 

 his successor, Mr. J. Ferguson, a list is given of the dates of 

 commencement of the little and big monsoons, from 1853 down 

 o 1892 inclusive. 



As a general result it is found that the average dates for the 

 little and big monsoons are April 20 and May 19, and that 

 when nothing particularly abnormal occurs, the big monsoon 

 may be expected to follow the little one in about a month. 



There are, however, considerable variations from this normal, 

 the little monsoon date ranging through 52 days, and the big 

 monsoon from May i to June 19. 



On looking over these variations it struck me that they would 

 probably be found to correspond to some extent with the rain- 

 fall of adjacent localities in India, especially the Carnatic 

 The result of a comparison of the anomalies is shown below — 



1864 

 1865 

 1866 

 1867 

 1868 

 1869 

 1870 

 1871 

 1872 



1873 

 1874 



187s 

 1876 



1877 

 1878 

 1879 

 1880 

 1881 

 1882 

 1883 

 1884 

 1885 



A mere glance at these figures shows at once a remarkable 

 parallelism both in signs and numbers. Thus in eighteen years 

 the signs are alike, neutral in three, and unlike only once. As 

 it is well known that the rainfall of the Carnatic was found by 

 Mr. Blanford to vary in a cycle of eleven years, closely corre- 

 sponding with that of the sunspots," the same ought to hold for 

 the anomalies in the dates of arrival of the big monsoon at 

 Colombo. As a matter of fact the relation appears to be still 



^ From the Ceylon Directory, 1892. 



- From the Rainfall of India, Part 11., Indian Meteorolocrieal Memoirs. 

 1887. ^ ' 



■' Mr. Blanford computed the probability of such a cycle as compared to 

 an invariable average to be as 655 ; i. Indian Meteorological Memoirs, 

 vol. iii. part 2, p. 244. 



