October 10, 1884. 



SCIENCE 



851 



in a fair way to be more amazed at their own 

 intellectual production than at any thing that 

 has 3"et happened in human history. 



LETTERS TO THE EDITOR. 



*** Correspondents are requested to be as brief as possible. 

 Th e icriter'sname is in all cases required as proof of good faith . 



The Hall effect. 



In your account of the proceedings of the section 

 of physics, at the Philadelphia meeting of the Ameri- 

 can association, occurs the passage: "He [Mr. Hall] 

 used not only gold-leaf, but strips of steel, tinfoil, 

 and other metals, and clamped them sometimes at 

 both ends, sometimes in the middle, and sometimes 

 only at one end; and in all cases the action was the 

 same, with the same metal, irrespective of the clamp- 

 ing." 



This statement is not accurate. I have subjected 

 soft steel only to the test here described, and I did 

 not with this metal try the experiment of clamping 

 it at one end only. 



Again, it is not quite accurate to say that Mr. Bid- 

 well attributes the action under discussion, to "one 

 edge [of the metal strip] being compressed and the 

 other stretched." One can best understand Mr, Bid- 

 well's explanation by examining the illustrations ac- 

 companying his article in the Philosophical magazine 

 for April, 1884. E. H. Halt.. 



Cambridge, Sept. 20. 



Iroquois pronouns. 



Allow me to correct the entire misconception of 

 my Montreal paper by your reporter of the anthropo- 

 logical section. I did not affirm that the "mission- 

 aries and all other authorities who have heretofore 

 written on the Iroquois languages were mistaken," 

 etc On the contrary, I proved that my conclusions 

 concerning the existence of an it, and the non-exist- 

 ence of on, were correct by quoting the ' exceptions' 

 and so-called ' idioms ' resorted to by the French mis- 

 sionaries to sustain their adaptation of the language 

 to the French form of two genders, etc. This ad- 

 aptation, which simplified the study for the young 

 priests, I affirmed would be folly for us to follow 

 when writing upon Iroquois construction for English 

 students. I proved my position by numerous ex- 

 amples from the best native authority, from those 

 who understood English or French as well as myself. 

 I might remark here that such authority presents a 

 vast contrast to that which the pioneer missionary 

 could obtain, and greatly facilitates investigation, I 

 could refer your reporter to ' vocabularies ' by long- 

 resident missionaries which to-day are worthless from 

 this fact. As to the 'English missionaries' referred 

 to, I know of none who have contributed to Iroquois 

 grammar. 



I mentioned Rev. Ashur Wright, an American, as 

 recognizing three genders; also Hon. Lewis Morgan, 

 author of the ' League of the Iroquois.' 



Upon so-called 'hazardous assertions' depends the 

 march of science, and I venture to re-assert, ' it still 

 moves.' Erminnie A. Smith. 



Jersey City, Oct. 1. 



Classification of Mollusca. 



In Professor Gill's instructive comment on mollus- 

 can classification, he unintentionally misquotes me. 

 The review in question said that no single instance of 



a calcified jaw ' occurs to us,' the two words in italics 

 (omitted by Professor Gill) making all the difference 

 between a positive assertion and a provisional one. 

 The Nautilus, as Owen, Lankester, and others state, 

 has been regarded as having a calcified jaw; and I am 

 quite confident that it is the single instance known 

 among recent mollusks. However, there is reason to 

 believe that the expression of Owen was used in a 

 less precise sense than has been supposed by later 

 writers, and that the calcification, if actually present, 

 is at most partial, and perhaps a mere individual 

 trait. In the only specimen of Nautilus I have had 

 the good fortune to be able to examine, the visible 

 parts of the jaw were wholly free from any calcifica- 

 tion. Whether the portions embedded in the mus- 

 cular tissue, or otherwise hidden from view, may have 

 been calcified, could not be determined, the specimen 

 being held too precious to dissect. The composition 

 of the jaw of Spirula is entirely like that of ordi- 

 nary cuttles, as far as the eye could determine ; and 

 it is evidently desirable that we should have further 

 investigation in regard to that of Nautilus. 



In regard to the Acephala, it does not seem to me 

 necessary that they should be ordinarily divided, un- 

 less good ordinal characters can be found ; and, if the 

 characters now used are imperfect, there is no reason 

 for retaining the divisions founded on them, except 

 in a provisional sense. 



I fully agree with Professor Gill, that the present 

 Dimyaria are not derived from the present Mono- 

 myaria; but whether both may not have had a 

 monomyarian ancestor, it is still too early to decide, 

 as it is (in a less degree) about the exact homologies 

 of the shell glands in Chitons and ordinary gastro- 

 pods, whose common characters seem to me largely 

 adaptive. 



It may be added, that while, so far as we know, 

 Ovulum has a purely involute shell, Pedicularia, in 

 its early stages, resembles, a small Erato with a dis- 

 tinct spire. W. H. Dat,i,. 



U.S. national museum, Oct. 4. 



The primitive Conocoryphean, 



Your notice of Mr. G. F. Matthews' s paper, read 

 before the British association, though complimentary, 

 gave no idea of the contents. Part of this commu- 

 nication was of exceptional importance. All accu- 

 rate histories of the development of single animals 

 are now thought well of ; but Mr. Matthews has 

 traced not only the transformations of the larval, but 

 the characteristics of the adult period, and the trans- 

 formations of old age. This author has also added 

 the general history of the evolution of some of the 

 most ancient groups of the trilobites, and shown that 

 the changes they pass through correspond with the 

 changes which the individuals of one of the groups, 

 the Ctenocephalus Matthewsi, passed through during 

 its growth. Opportunities for doing this sort of work 

 are rare, and the men who do it still rarer. 



Alpheus Hyatt. 



[It was impossible for us, in the brief space at com- 

 mand, in reporting promptly two scientific meetings 

 of a week each in quick succession, to do justice to 

 any paper. Many were altogether omitted. — Ed.] 



Book-postage in the United States. 



In reference to your remarks on the expense of 

 using libraries through the mails, allow me to point 

 out that this expense is in America exactly double 

 what it is, and has been for many years, in England, 

 and even in Canada. The English and Canadian 



