Jan. 9, 1879] 



NATURE 



^ZZ 



devoted to the lower forms, the specimens selected being enor- 

 mously magnified, coloured, and exhibiting all details both of 

 external and internal structure. 



" The Year Book of Facts in Science and the Arts," edited 

 by James Mason (Ward, Lock, and Co.), is little better than a 

 scrap-book of cuttings from various papers ; we don't suppose it 

 is seriously intended to represent the science of the past year. 



Messrs. Hardwicke and Bogue have issued a second 

 edition, "revised and corrected," of Mr. M. P. Edgeworth's 

 work on " Pollen," noticed in oiu- columns on its first publica- 

 tion (Nature, vol. xvi. p. 499). 



At the last meeting, December 6, of the Russian Geographical 

 Society, Col. Rykatchoff made a commimication on the difficulty 

 of organising obser\-ations on rain and storms. — Prof. Meller 

 made a very interesting communication on the former connection 

 between the Sea of Azov and the Caspian. The character of 

 the geological formations en the tract between both seas proves 

 without doubt that during the tertiary epoch the waters of both 

 were connected ; thus organic remains of Caspian origin are 

 found within eighty-seven miles from the actual shores of the 

 Sea of Azov. 



At the last meeting of the St. Petersburg Physical and Chemical 

 Society, Prof. Beketoff made a communication on the atomic 

 heat-capacity of hydrogen when mixed with palladium. He 

 determined it as equal to S'86, i.e., very near to that of cop" er 

 and silver. 



Those of our readers who are in the habit of using chemical 

 apparatus should get the Revised List just issued by Mr. Fletcher, 

 of Warrington, who deserves credit for the very successful efforts 

 he makes to introduce improvements into this department. 



The much-talked-of canal between Delaware and Chesapeake 

 Bays, which will shorten the water-route from Baltimore to New 

 York and Europe by 225 miles, is now at last to be constructed. 

 Its length will be seventeen miles, and the cost is estimated at 

 four million dollars. It will run through the Sassafras Valley 

 and will have no locks. 



The additions to the Zoological Society's Gardens during the 

 past week include a Punjaub Wild Sheep {Oz'is clydbceros) from 

 India, presented by Col. W. R. Alexander ; two Califomian 

 Quails (Callipepla calif ornica) from California, presented by 

 Mr. William Turquand ; seven Brown Tritons {Geotriton fuscus). 

 South European, presented by Prof. H. H. Giglioli, C.M.Z.S. • 

 a Feline Dowrocouli {Nyctipithecus felimis) from South America 

 purchased. 



FURTHER RESEARCHES ON THE SCINTIL- 

 LATION OF STARS 



CINCE last we reviewed M. Montigny's valuable researches 

 '^ on the scintillation of stars (vol. xviii. p. 292) he has 

 again published some highly interesting details. The re- 

 searches now in question refer specially to the changes of colour 

 which characterise the scintillation of the red and ^orange stars. 

 M. Montigny tried to solve the question whether the changes of 

 colour in scintillation follow certain definite laws; whether, 

 for instance, their relative fi-equency expressed in numbers, shows 

 differences which depend on the nature of the star's own light, 

 on the star's elevation above the horizon, or on the condition of 

 the atmosphere. 



In order to solve this complicated question, it was divided 

 into Its several parts. First of all M. Montigny investigated the 

 mfluence of the star's own light and that of the condition of the 

 atmosphere upon those colours which characterise the scintilla- 

 tion of the stars of the so-called third type. Our readers will re- 

 member that these are the stars which show black lines as well 

 as dusky bands in their spectra ; they are generally of a red or 

 orange colour, and mostly variable. There are not many fine 

 stars m this class, the most remarkable ones are ab^ut thirty in 



number, and M. Montigny has examined only the following 

 fifteen : — jS Andromedae, a Ceti, p Persei, Aldebaran, Betelgeuze, 

 a Hydr^e, Arcturus, 5 Virginis, 5 Coronse, o Serpentis, Antares, 

 a Herculis, 7 Aquilse, and /3 and « Pegasi. The evenings of 

 obser\'ation now number 476, and reach from October, 1870, to 

 February, 1878. 



The way in which the obser\'ations were made was the follow- 

 ing : — After each evening of observation not only the values for 

 the intensity of scintillation were entered for each star, reduced 

 to a distance of 60° from the zenith, but each single colour ob- 

 served in the circular image was also noted do^vn. Further, the 

 observations made in wet weather were noted separately from 

 those made during dry weather. Finally the various colours 

 were entered on a table divided into seven columns, respectively 

 headed — red, orange, yellow, green, blue-green, blue, and violet. 

 The sum total of any column thus indicates the number of times 

 which the colour in question was obser\ed in a certain star. 

 Arcturus, for instance, in 131 observations during moist weather, 

 showed the red colour 130 times and blue 1 18 times. These 

 nimibers thus express the absolute frequency of these two colours. 

 If we compare the number 130 for red, with the sum total of all 

 colomrs shown by Arcturus during rainy weather, which is 491, 

 then we obtain the relative frequency of red, which is o'265, or 

 multiplied by 1000 = 265. Therefore in 1000 changes of colour 

 which appeared in Arcturus during rainy weather, red occurred 

 265 times, and blue 240 times. 



In the following table we give the average frequencies of the 

 different colours for the fifteen stars of the third type enumerated 

 above ; line A shows the frequencies obser\ed in rainy weather, 

 and B those observed in dry weather. The total of observations 

 was 800 for A and 36S for B ; the totals of the changes of colour 

 observed were 2,982 for A and 1,368 for B. 



Intensity. Red. Orange. Yellow. Green. _ "p" Blue. Violet 

 A ... 60 272 194 239 57 4 230 3 



B ... 43 278 213 222 63 5 216 4 



Average 52 275 204 230 60 5 223 4 



We observe in this table that (i) the relative frequency of red 

 is far greater than that of any other colour in rainy weather as well 

 as in (&y ; (2) red, green, and particularly orange are seen more 

 frequently in dry weather than in wet ; (3) the frequency of 

 yellow and blue is on the contrary greater in wet weather than 

 in dry. 



Although the differences in the frequency of one and the same 

 colour, according to the state of the atmosphere, are rather 

 limited, they nevertheless indicate an important fact. It is also 

 remarkable that the numeric differences in the complementary 

 colours red and green on the one hand, and blue and yellow on 

 the other, lie in the same direction- It is further worthy of 

 notice that the greater frequency of blue in rainy weather agrees 

 well with the fact that blue greatly predominates during such 

 weather in the image of the star as shown by the scintillometer. 

 This predominance of blue has also been frequently observed a 

 short time previous to rainy weather. 



The following table will be found interesting, as it contains 

 the changes of colour and intensity of scintillation of the six 

 brightest stars of the third type. In line I. are those of Betel- 

 geuze, which is orange coloured, and the spectrum of which 

 shows numerous broad bands, dissolvable into lines ; line II. 

 gives those of Aldebaran, pale red, whose changing spectnun 

 has many well-defined lines and dark bands; line III. represents 

 Arcturus, yellow-orange, with numerous dark lines not united 

 into bands in its spectrum ; line IV. gives those of a Hydrse, a 

 yellow star with very dark lines in the spectrum ; line V. those 

 of Antares, red, with wide bands and very distinct lines ; and 

 line VI. those of a Herculis, yellowish red, with black lines and 

 dark bands. 



Intensity. Red. Orange. Yellow. Green. Blue. Violet. 



I. Betelgeuze ..65 255 190 234 106 202 13 

 II. Aldebaran ... 62 255 186 232 104 210 13 



III. Arcturus ...61 253 120 246 130 219 32 



IV. aHydrse ...55 284 162 253 113 188 — 

 V. Antares ... 53 266 121 245 130 219 33 



VI. a Herctalis ... 47 275 225 232 51 217 — 



Average 57 265 167 240 106 209 15 



These values show that the relative frequencies of the three 

 principal colours, red, orange, and blue, remain within narrow 

 limits for the six stars. Yet red seems to increase in frequency 

 in the three last stars, two of which are of -a decided red tint. 



