Oct. 2, 1879] 



NATURE 



533 



swept over the face of the mountain, driving the rain in 

 almost horizontal sheets along the surface. From time 

 to time mists floated over the mountain, and it was 

 bitterly cold. 



Iceland a Meteorological Station. — If Iceland were 

 connected with the Faeroe Islands, and with the 

 north of Scotland by telegraph, there can be no doubt 

 that it would form a valuable meteorological station, 

 although from the various disturbing influences the effect 

 of which would be comparatively local, such as the jokuUs 

 and the various local currents, such a station would be 

 less valuable than would be afforded by a vessel moored 

 600 or 800 miles out in the Atlantic between Ireland and 

 Newfoundland, and in telegraphic communication with 

 the central office in London. 



Drift Wood of Iceland.— QxQzX quantities of drift wood 

 are thrown upon the southern coast of Iceland. It is 

 said to be chiefly fir, and it is asserted by some to come 

 from Siberia by an arctic current, and by others from 

 America by the Gulf Stream. We noticed that the coast 

 between Grindavik StaSr and Cape Reykjanes was far 

 more thickly strewn with drift wood than the coast more 

 to the east in the neighbourhood of Eyrarbakki. As the 

 Gulf Stream impinges on the south-western peninsula, it 

 would seem that it must therefore be the chief source of 

 the drift wood. The trees that we saw were torn up by 

 the roots, and they were completely blanched, and in 

 many cases riddled with holes by some species of borer. 

 A portion of the skeleton of a large whale was visible 

 on the shore near Grindavik. 



Improvements in Iceland. — During the year which has 

 elapsed since we last visited Iceland, several very marked 

 improvements have been set on foot. In no respect is 

 this more conspicuous than in the case of the roads. A 

 iz^ years ago a writer made the assertion " there are no 

 roads in Iceland." At the present time road-making is 

 making great progress, and many scores of miles of 

 excellent roads exist. Of course we mean such roads as 

 alone are possible, without great expenditure of money 

 and labour, in a country which is one vast volcano. 

 Driving roads are impossible, but excellent pony roads 

 are being constructed, and will greatly facilitate despatch 

 of business and intercommunication. The first bridge in 

 Iceland is about to be commenced. It will cross the 

 Olfus^, and materially help to establish a better commu- 

 nication between the east and the west. A second bridge 

 is to be thrown across the Thjorsa. The first lighthouse 

 in the island was erected a year ago, and the light- 

 dues paid by ships at the port of Reykjavik have already 

 almost paid for its construction. There is some talk of 

 founding a school of farming at MoSrudalr in the north- 

 west, and a law school in Reykjavik, where a divinity 

 school and a medical school already exist. In Reykjavik 

 new houses are being built ; there is a proposition on foot 

 to build an hotel, and a new house for the Althing, which 

 now holds its biennial meetings in the Latin school. 

 Hafnafjord and Eyrarbakki are flourishing little ports ; 

 Akureyri does a fair trade in shark liver oil, and in ponies ; 

 and the Krisuvik sulphur mines appear to be in good 

 working order, and to yield a rich product. 



Reykjavik, September 2 G. F. RODWELL 



ON HARMONIC RATIOS IN THE SPECTRA 

 OF GASES 



PROF. G. JOHNSTONE STONE^has given in the 

 April number of the Phil. Mag. for 1 87 1 some remark- 

 able ratios of the wave-lengths of three of the hydro- 

 gen lines. Prof. Sorct and Mr. Lecoq de Boisbaudran 

 have also given several similar ratios, and I have found at 

 various times a great many. It is, however, impossible to 

 decide, without a thorough discussion, how many of these 

 harmonic ratios may be due to accident. All possible 

 fractions in a given spectrum ought to be calculated, and 



we could then see, by the theory of probability, whether 

 the coincidences with ratios of comparatively small num- 

 bers are more numerous than we ought to expect. I 

 began this work about a year ago. The calculation and 

 discussion of twenty thousand fractions will necessarily 

 take some time. The following simple ratios, however, 

 which I have found in the iron-spectrum, I believe to be 

 worth recording. I may say that I have gone only through 

 the seventh part of that spectrum as yet. The first 

 column in the following table contains the corrected wave- 

 lengths of iron lines as given by Angstrom. If these 

 numbers are multiplied by the fractions given in the 

 second column, we obtain the calculated values of other 

 iron lines. The observed values and difference are given 

 in the fourth and fifth columns. 



The difi-erences could of course be reduced to one-half 

 by throwing part of them on the possible errors in the obser- 

 vation of the wave-lengths given in the first column. It 

 is to be remarked that the intensities of the iron lines 

 which figure in the above table are as a rule very strong. 

 Thus all but three of the lines have an intensity of over 

 six attached to them in Watts' Index. 



The following table contains a set of iron lines, which 

 can be arranged as harmonics of a fundamental vibration 

 whose wave-length is 0-018694765 of a millimetre. 



The table is arranged according to the pattern of that 

 given by Prof. Stoney for the hydrogen lines. 



I have included the forty-fourth harmonic, because 

 Thaldn gives 4248-8 for the observed value of the wave- 

 length, which reduces the difference to zero. I must, of 

 course, complete the investigation before I can definitely 

 say in how far all these coincidences may be due to acci- 

 dent. On the whole, as far as I have hitherto gone, the 

 result does not seem to be decisive in favour of such a 

 simple connection between the wave lengths of different 

 lines. The true law of the distribution has not yet, I 

 believe, been found, but harmonic ratios may take a 

 secondary part. Arthur Schuster 



OUR ASTRONOMICAL COLUMN 

 Palisa's Comet.— The following elements of 



this 



comet have been calculated by Mr. Hind from the first 

 Pola observation on August 2 1 , one at Leipsic on August 28, 

 and M. Henry's observation at Paris on September 11: — 



