292 



NA TURE 



{July 27, 1882 



Baker, F.R.S., of Kew Gardens. Mr. Lucas is by no 

 means backward in acknowledging by whom he has been 

 aided in the completion of the work, and amongst others 

 there are numerous and valuable contributions by Mr. J. 

 R. Dakyns, M.A., Cantab, (of H. M. Geological Survey), 

 both in the foot-notes and in the text. 



Notwithstanding this, however, the book is an original 

 work, everywhere bearing abundant evidence that the 

 materials have not been compiled, but in great part col- 

 lected upon the spot, and carefully worked out by the 

 author himself. And as there are many secluded valleys 

 in Cumberland, Westmoreland, and Yorkshire, in which 

 the customs, manners, and folk-speech differ very little 

 from that of Nidderdale, we think the volume deserves a 

 much wider circulation than in the district of that valley 

 from which it takes its name, Six of the concluding 

 chapters are devoted to the birds of Nidderdale. These 

 chapters on natural history are the most pleasing in the 

 book, and contain information respecting the distribution 

 of many birds which is altogether new. After these there 

 is a well-told story in the dialect ("Dicky and Micky 

 Date") by Thomas Thorpe. 



Probably the most valuable, and certainly the most 

 laborious portion of the work, is the glossary of the 

 dialects of Nidderdale, with which it concludes. 



Local glossaries no doabt there are without number, of 

 the northern dialects, bat we have never before seen one 

 which has traced with such clearness, both from its use 

 and derivation, each word to its source. A residence of 

 over forty ye irs in some of those remote regions in which 

 a corresponding dialect is spoken, enables us to testify 

 that Mr. Lucas has been wonderfully accurate and ex- 

 haustive in laying hold of the vocables of the district ; 

 and the pains and skill with which he has traced them 

 through the Norse and other cognate languages, must be 

 seen before they can be properly understood. T. E. 



LETTERS TO THE EDITOR 



[The Editor does not hoi J himself responsible for opinions expressed 



by his correspondents. Neither can he undertake to return, 

 or to correspond wit': the writers of, rejected manuscripts. 

 No notice is taken of anonymous communications. 

 [The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impoi to ensure the appearance even 



of communications containing intei csting and novel /acts.] 



The Sun-spot Period 



The sight ol 00 olf's sun-spot curve 



cen the years 1706 and 1799, so clearly plotted in the 

 lion by Prof. Stanley Jevons, on "The Si 

 mercial Cycle" (Nature, vol. xxvi. pp. 226-2S), impels me to 

 offer some remarks having special reference to solar periodicity 

 at thai i 



In a paper read at the meeting of the British Association in 

 York la^t year, 1 ascribed the sun-spots to planetary tides in the 

 solar atmosphere, [t is not pretended that what was advanced 

 ation, but the assumption had this prac- 

 tical result — it led me to the conclusion (hat the sun-spot maxima 

 and minima, recognised in whal is known as the sun-spot period, 

 are, on the whole, determined by the relative positions of the 

 planets Venus, Earth, and Jupiter. The maxima are nearly 

 ciated villi configurations in which Venus and Earth 

 in conjunction or opposition, have Jupiter in or near syzygy 

 or quadrature ; while the minima are even more certainly asso- 

 ciated with configurati ins in which Venus and Earth in conjunc- 

 tion or opposition, have Jupiter in or near the octant. 



There are, however, significant deviations from this general 

 law, and the maximum to which Wolf assigns the dale lybS'I 

 occurs at a time when the law would give a minimum. Now it 

 may bo admitted, that at times special conditions prevail, arising 

 from changes within the sun itself, or from the advent of mate- 

 rial agglomerations foreign to our system. I prefer, neverthe- 

 less, to assume for the present, that the explanation of such 

 periodicity as has been established is within the resources of a 

 planetary hypothesis. Accepting the sun-spot record as read for 



us by Prof. Wolf, because we have 11 'thing belter, it is inferred 

 that the apparent anomalies of ihe period in question are due to 

 exceptional planetary configura 1 



The following statement shows how lamentably observation 

 and theory are at variance, in regard to the sun-spot numbers, 

 near the dales 1778 and 1789 : — 



Years of Maximum Annual Sun-Spot Numbers 



Observation 



1761 1769 1778 17S9 1804 



Hypo: I 

 1761 1771 1783 1794 1S04 



The remarkable series of corn-prices, as given by TYof. Jevons, 

 however shows maxima so fairly in accord with the hypothetical 

 maxima that I am tempted to quote them : — 



Years of Maximum Corn-price at Delhi 

 1763 1773 17S3 1792 1803 



If this relation is anything more than a coincidence, an important 

 question arises. Arc we to consider the sun-spot record 

 defective, and reject the maxima of 177S and 1789, because 

 they cannot be traced in the corn-prices? Not necessarily, it 

 seems to me. The sun-spot record may not be reliable, and w itli 

 its revision difficulties may vanish, but there is something ver\ 

 substantial about the maximum of 1789, and it must be remem- 

 bered that it is one thing to measure a sun-spot, and quite 

 another thing to use a sun-spot as a measure. The sun-spot tells 

 of solar disturbance, but the attendant changes in solar radiant 

 forces will be changes in quality as well! as in quantity, and it 

 may be taken for granted that there are solar periods that are not 

 to be found in the sun-spot numbers directly. One outcome of 

 the researches of Dr. Koppen has been the recognition of what 

 is called the period of the " Umkehrung," or inversion, so 

 named because the more usual relations of sun-spots and air 

 temperatures are su, posed to be reversed during this particular 

 period, which lies between the years 1770 and 1816, or there- 

 abouts. Double-edged weapons are, however, dangerous, and 

 must be used with caution. 



.Sun-spot measurement itself is a somewhat arbitrary process. 

 The "relative number" for a given day is ten times the 

 number of groups, plus the number of individual spots; while 

 the method initiated by the Kew observers, and now adopted at 

 Greenwich, gives "spotted area," that is, the proportion of the 

 sun's surface covered by such spots as may be visible on that 

 day. It would be interesting to compare the positions of the 

 , seen in April last, as given on the annual sun-spot 

 rolls at Zurich and Greenwich respectively. Moreover, certain 

 well-marked distinctions in the character of the disturbance 

 have no place, or next to none, in sun-spot measure — the 

 faculai are ignored, while umbra and penumbra are lumped 

 together. 



It should be remarked that observation and hypothesis agree 

 in the total number of periods, so that, the length of the mean 

 sun-spot period remains unaltered, unless it is decided thai 

 certain observed maxima may be taken in addition to the hypo- 

 thetical maxima, and not as replacing them. The planetary 

 hypothesis requires that the sun-spot scries shall be considered as 

 a compound series, representing a number of more or less im- 

 portant series of planetary periods, and it is to be expected that 

 at limes there will be a difficulty in tracing any dominant series 

 of periods, whether primary or derivative. 



It seems to me that too much importance is apt to be attached 

 to the mean sun-spot period, seeing that its occurrence is excep- 

 tional, and the departure from it very considerable. 



That these observations should be inconclusive is a matter of 

 course, but my purpose will be served, if they tend to produce 

 the impression, that there may be no real solution of continuity 

 in the relation between the sun-spot numbers and the particular 

 series of planetary periods that 1 believe to give "the sun-spot 

 period " a rational basis. F. B. Edmonds 



72, l'ortsdown Road, London, W., July 14 



Messrs. McAlpine's Atlases 



Will you allow me space in your columns to make a few 

 remarks upon the "Biological Atlas" of Messrs. D. and A. 

 McAlpine, and the "Zoological Atlases" of the first of these 

 gentlemen ? 



Mr. D. McAlpine was, some three or four years ago, a student 



