January 22, 1886.] 



SCIENCE. 



73 



of address as would be literally appropriate only 

 from children of the master of the house. Many 

 have houses and farms of then* own, giving a 

 share of the crop to the master, who can, but 

 rarely does, claim the whole of it. Slaves can 

 use their earnings to buy then- freedom if they 

 can accumulate enough to do so, and they are 

 frequently owners of other slaves. They generally 

 make their own bargains for wages if they go out 

 as porters or domestics, and reckon with then- 

 owner themselves. The condition of the slaves is 

 much harder, however, among the Sakalavas, in 

 the north-east part of the island, — a tribe hostile 

 to the Hovas, and still pagans, by an alleged 

 treaty with whom the French have acquired those 

 : rights ' which they have for some years been 

 vainly endeavoring to enforce upon the Hovas. 

 With the latter, since their conversion to Chris- 

 tianity, a gradual and important amelioration has 

 taken place in the matter of slave-holding, and the 

 families of criminals are now no longer liable to be 

 sold into a state of servitude. 



ASTRONOMICAL NOTES. 



The zodiacal li^ht. — Professor Searle of Har- 

 vard college observatory, in a paper recently 

 published, has continued his interesting investi- 

 gations on the zodiacal light. This peculiar 

 phenomenon is supposed to be due to finely 

 divided matter of some kind illuminated either 

 by direct sunlight or by the result of electrical or 

 chemical action. This matter may be only a por- 

 tion of the atmosphere or of some cosmical mass 

 more or less homogeneous, but illumination is 

 presumed to be confined within certain limits ; 

 and the difficult task of the observer has been to 

 attempt to define these limits. As a result of 

 the present inquiry, there would seem to be reason 

 to think, that after allowing for atmospheric 

 absorption, which probably affects the apparent 

 position largely, the zodiacal light, as seen during 

 the second half of the nineteenth century, has 

 had a more northern latitude near the longitude 

 180° than near the longitude 0°. Furthermore, 

 from a careful study of the distribution of the 

 stars in the Durchmusterung, Professor Searle 

 shows, that, "upon the meteoric theory of the 

 zodiacal light, it is to be expected that a con- 

 tinuous zodiacal band should be present ; but the 

 question of its actual visibility is complicated by 

 the slight maxima of stellar density which are 

 situated along those parts of the ecliptic most 

 readily accessible to observation from stations 

 in the northern hemisphere." And finally, from 

 an examination of the elements of the first 237 

 asteroids, it would seem that the belt of sky 



occupied by the projections of then' orbits pre- 

 sents certain peculiarities which correspond to 

 those of the zodiacal light, and suggest the 

 hypothesis that the light may be partly due to 

 minute objects circulating in orbits like those of 

 the smaller planets. 



U. S. naval observatory. — Vol. xxix. of the 

 publications of the Naval observatory, now in 

 press, will contain, in addition to the regular 

 series of astronomical and meteorological obser- 

 vations for 1882, a valuable appendix by Professor 

 Hall on the orbit of Japetus, the outer satellite of 

 Saturn ; an appendix by Professor Harkness on 

 the flexure of transit instruments ; and a third 

 appendix by Commander A. D. Brown, giving 

 the observations of the partial solar eclipse of 

 1885 March 16, made at the observatory, and also 

 observations made by several volunteer parties 

 near the line where the annular phase was visible. 



Lord Rosse's observatory, Birr castle. — We 

 have recently received two papers communicated 

 by the Earl of Rosse to the Royal Dublin society, 

 and reprinted from vol. iii. (second series) of the 

 Scientific transactions of the society. The first 

 of these papers is a series of notes by Dr. Boed- 

 dicker, on the aspect of the planet Mars in 1884, 

 accompanied by a lithographed plate giving thir- 

 teen sketches of the markings on the planet's sur- 

 face. The second paper is also by Dr. Boeddicker, 

 and contains the results of observations made on 

 the changes of heat from the moon during the 

 total eclipse of 1884 Oct. 4. From these observa- 

 tions it would appear that the amount of heat 

 radiated to us from the moon itself, as distin- 

 guished from that merely reflected or diffused 

 by it, is almost insensible ; and the minimum of 

 the heat effect falls decidedly later than the 

 minimum of illumination. 



NOTES AND NEWS. 



For many years the exorbitant tax on salt 

 in India has oppressed the lower classes, almost 

 extinguishing some branches of industry. The 

 Indian government has at last become alive to 

 certain objections to the present rates of the salt- 

 tax ; namely, that cattle are stinted of a supply 

 of salt, and that the same duty is charged on salt 

 employed in manufactures or agriculture as for 

 that used for other purposes. Experiments, for 

 some time unsuccessful, have been prosecuted 

 with a view of discovering a process whereby salt, 

 while still useful for manufactures and agricul- 

 ture, could be rendered unfit for human consump- 

 tion. The government has now offered a reward, 

 not exceeding five thousand rupees, to the inven- 

 tor of a process satisfying the following condi- 



