872 



SCIENCE. 



[N. S. Vol. XV No. 387. 



For this purpose, accepting Dr. Stokes's de- 

 termination of the density of marcasite at 4.88, 

 the formula given in my paper (page 178) 

 would assume the form 



17496 



■ 3485, 



in which x represents the percentage propor- 

 tion of marcasite in the specimen under trial, 

 and a the specific gravity of the specimen. 



So far as these specimens go, there appears 

 a fair approximation between the results of the 

 chemical method and those founded on density, 

 except in three cases (Nos. 9, 11 and 23), all 

 from lead-mines in Wisconsin, in which Dr. 

 Stokes detected the common enclosure of 

 galenite, etc. Obviously the above series is 

 not well chosen to afford a certain decision 

 either way; only a series of crystallized speci- 

 mens, with densities lying hetween the datum- 

 points, 5.02 and 4.88, could be of service for 

 satisfactory comparison. Therefore it appears 

 to me that this second inference of Dr. Stokes 

 also remains unproved. 



The main object of my own paper in 1887, 

 however, was the establisliment of a principle 

 of practical bearing and importance, in refer- 

 ence to roofing slate, coal and building-stone. 

 This was the connection of the stability of the 

 pyrites, whether marcasite or pyrite, in resist- 

 ance to atmospheric agencies of decomposition, 

 with the higher densities of these minerals, 

 i. e., in their ordinary forms of distribution in 

 nature, apart from association with other sul- 

 phide-ores. It was there stated (page 222) 

 that ' the highest stability can be expected only 

 from samples of crystallized marcasite or 

 pyrite whose specific gravity exceeds 4.99 * * * 

 though little danger from decomposition may 

 be expected down to a specific gravity 4.97.' 

 This subject has not been considered in the 

 paper of Dr. Stokes, has no necessary depend- 

 ence on either of the purely hypothetical views 

 already discussed, and the above conclusion, I 

 believe, so far remains unquestioned. 



Alexis A. Julien. 



Columbia University. 



coiled basketry. 

 To THE Editor op Science: May I say that 

 no coiled basketry of any kind was made 

 by the Indians of North America east of 

 the Rocky Mountains ? In the books there 

 does not seem to be one illustration of 

 coiled work taken from the surface of 

 ancient pottery in this area. I am aware that 

 in the Appalachians, and especially among 

 the Cherokees, there is a kind of bread tray 

 made of straw and sewed with wooden splints, 

 after the old-fashioned beehive, but I am not 

 positive that these are of pre-Columbian ori- 

 gin ; second, that a little coiled work was done 

 by the Comanches, but they are Shoshonean, 

 and belong west of the Rockies; third, 

 that the Mackenzie River hunting bags of 

 babiche are coiled, but the makers are Atha- 

 bascan; fourth, that the Central Eskimo make 

 poor trinket baskets in coiled work which look 

 dreadfully modern. With these facts in mind 

 I am not prepared to say, without the permis- 

 sion of my colleagues, that the ancient tribes 

 east of the Rocky mountains knew anything 

 in the world about coiled basketry. 



0. T. Mason. 



THE MUD SHOWER. 



Noticing in Science of May 2, p. 718, an 

 account of a 'mud shower' at Easton, Pa., on 

 April 12, by J. W. Moore, I wish to record 

 the fact that a similar shower was observed 

 at New Haven, Conn., on the same day, but 

 between 4 and 5 p.m., instead of noon. White 

 clothes hanging on lines in the yards were 

 spotted in a very annoying way, every drop of 

 rain leaving a mud-colored spot. The same 

 kind of spots appeared on the window glass 

 of houses. Ladies who attended the ball 

 game that afternoon had their clothes badly 

 spotted, showing that the shower here covered 

 a considerable area, for the game was played 

 on grounds in the suburbs. The shower was 

 a slight one, of short duration, but every sep- 

 arate drop seemed to be charged with dirt. 

 Tiiere had been showers of clean rain on the 

 previous day. Is it not possible that the dirt 

 was cosmic dust or of meteoric origin? 



A. E. Verrill. 



