March 27, 1885. 



SCIENCE 



249 



ing (March 11), are, Jupiter, yellow; Regulus, blue. 

 The naked-eye view is very similar to the double star 

 $ Cygni, when seen with a power of about one hun- 

 dred. Struve calls the color of Eegulus bluish white ; 

 but its color now appears decidedly blue, or greenish 

 blue. 5, 



Acquisition in infants. 



I recently tried teaching Constance A., twelve 

 months old, to ring a common dome table-bell. Per- 

 ceiving the little knob on top to be somehow con- 

 cerned, she fingered it clumsily, but could not learn 

 to strike down on it accurately with her raised hand, 

 though I forced her to do so many times. She made 

 clumsy motions, but finally, half accidentally, she 

 rang it. This was enough. She at once rang it 

 repeatedly with great success. I took it away to 

 test her memory, and the next morning she rang it 

 immediately without suggestion, but had it for a mo- 

 ment only. She was then absent four days : on return- 

 ing, she rang it at once. C. 



Devonian strata in Montana. 



The following note is written simply to place upon 

 record the first positive identification of Devonian 

 strata in the Rocky-Mountain region of Montana. 



In 1872 the Hayden survey brought in, from several 

 localities in the territory, collections of fossils, con- 

 sisting mainly of separate valves of brachiopods em- 

 bedded in a hard limestone. They were examined by 

 Prof. F. B. Meek, who found that the species were 

 mostly new, and that the genera represented were, 

 without exception, common to both the carboniferous 

 and Devonian, while a small proportion was also rep- 

 resented in the Silurian. In Hayden's sixth annual 

 report, p. 432, Professor Meek says, " Some of the 

 Producti, Chonetes, and Spirifer have rather a Devo- 

 nian look, while a very finely striated Hemipronites 

 is very similar to some of the Devonian types of that 

 genus. Even the form I have referred to, H. crenis- 

 tria, is quite as nearly like some varieties of H. 

 chemungensis (Streptorhynchus chemungensis, of the 

 fourth volume, Paleont. New York), from the Che- 

 mung and Hamilton groups of the New- York Devo- 

 nian, as it is like the carboniferous forms of H. crenis- 

 tria." However, notwithstanding the resemblance of 

 the fossils to Devonian forms, he regarded the whole 

 collection as belonging to the lower part of the carbon- 

 iferous, as it contained no strictly Devonian types 

 of corals, crinoids, or lamellibranchs. He at the same 

 time stated his belief that they were referable to a 

 lower horizon than the other carboniferous collections 

 brought in from adjacent portions of Montana at the 

 same time. The specimens examined by Professor 

 Meek were mainly from the mountains on the south, 

 east, and north sides of the Gallatin valley. During 

 the summer of 1884, the writer, in company with Dr. 

 F. Y. Hayden, had occasion to revisit a portion of 

 this area. In a section made at a point four or five 

 miles north-west of Hamilton, running north-west- 

 wardly from the Gallatin River, a collection of fossils 

 was obtained from beds which at the time were sup- 

 posed to be of lower carboniferous age, and which 

 were colored carboniferous on the geological map 

 made in 1872. Upon returning from the field, the 

 specimens were submitted to Mr. Charles D. Walcott 

 of the geological survey, who identified them as un- 

 doubtedly Devonian. The following lists were pre- 

 pared by him. List No. 2 includes some specimens 

 obtained from a locality three or four miles north- 

 east of the point from that where those in the first 

 list were found. 



Devonian fossils from north-east of Gallatin Paver, 

 Montana. 



List No. 1. — Discina lodensis Hall (?); Strepto- 

 rhynchus chemungensis Conrad ; Orthis Yanuxemi (?) 

 Hall(?); Chonetes mucronata Hall ; Productus lach- 

 rymosus, var. limus Conrad; Productus speciosus; 

 Spirifera disjuncta Sowerby; Spirifera Engelmanni 

 Meek; Rhynchonella pugna Martin; Rhynchonella 

 sinuata Hall; Rhynchonella tethys Billings (?) ; 

 Atrypa reticularis Linnarsson; Ambocoelia um- 

 bonata Conrad ; Athyris hirsuta Hall ; Athyris 

 sp.(?); Aviculopecten ; Grammysia, 3 sp. ; Modio- 

 morpha; Nucula; Schizodus. 



List No. 2. — Streptorhynchus chemungensis 

 Conrad; Spirifera sp.(?); Rhynchonella Horsfordii 

 Hall ( ?) ; Athyris hirsuta Hall. 



Mr. Walcott says, " Of the twenty- three species of 

 fossils given in lists 1 and 2, twelve are identical with 

 species occurring in the upper Devonian of the Eureka 

 district, Nevada: of the others, two are upper Devo- 

 nian species in New- York state, and Athyris hirsuta 

 occurs at the base of the carboniferous, in the Eureka 

 district. There is also a species of Athyris too im- 

 perfect for determination. The remaining forms are 

 lamellibranchs belonging to five genera; and the 

 species closely resemble those of the lower carbo- 

 niferous, of the Eureka district." The latter were 

 obtained from the upper portion of the bluff from 

 which the specimens were obtained. 



A. C. Peale, 

 IT. S. geological survey. 



The Hall effect. 



About a year ago Mr. Shelf ord Bid well published a 

 table intended to show that the direction of the mag- 

 netic rotation of the equipotential lines of an elec- 

 tric current in any given metal could be inferred 

 from the sign of the effect produced by stress upon 

 the thermo-electric property of the metal. 



Although Mr. Bid well's attempted explanation of 

 the former effect by means of the latter has proved 

 entirely inadequate, the table published is neverthe- 

 less interesting and suggestive. It appears, however, 

 that the law indicated in this table is not perfectly 

 general. Mr. Coggeshall and Mr. Stone of the pres- 

 ent Harvard junior class, working with my co-oper- 

 ation at the Jefferson physical laboratory, find that 

 French cold-rolled steel would form an exception in 

 Mr. Bidwell's table, acting in the thermo-electric test 

 like copper, but in the other test like iron. Their ex- 

 amination of copper and iron confirms Thomson's 

 results with those metals, and, as a necessary conse- 

 quence, Mr. Bidwell's table. 



The students have examined only these three met- 

 als as yet, but will probably extend their investiga- 

 tion to others. E. H. Hall. 



Cambridge, March 20. 



P.S. — We have now taken a t strip of aluminium, 

 cut two pieces from it, and teste'd one of these pieces 

 for the transverse effect, the other for the thermo- 

 electric effect. The transverse effect is like that 

 in copper. This agrees with the result of my pre- 

 vious examination of aluminium, but does not agree 

 with the result obtained by Mr. Bidwell. The ther- 

 mo-electric effect was like that in iron. This does 

 agree with the result found by Mr. Bidwell. Hence 

 this specimen of aluminium, which is not the same 

 that I originally used, makes another exception in 

 Mr. Bidwell's table. E. H. H. 



