June 29, 18S3.1 



SCIENCE. 



601 



3. Secondary group (mesozoic). 



Triasssic system, violet. 



Jurassic " blue (lias, dark bbie). 



Cretaceous " yreen. 



4. Tertiary group (cenozoic), yellow, using light- 

 er shades as the beds become more recent. 



5. Quaternary deposits. Decision referred to the 

 committee of the map of Europe. 



6. Resolutions of detail relative to shades, reserves, 

 etchings, and letter notations. 



Ill Rules concerning the nomenclature of 

 species. 



1. The nomenclature adopted is that in which each 

 animal and plant is designated by a generic name 

 and a specific name. 



2. Each one of these names is composed of a sin- 

 gle Latin or Latinized word, written according to the 

 rules of Latin orthograpliy. 



3. Each species may present a certain number of 

 modifications, related to each other in time or in 

 space, and designated respectively under the name of 

 mutations or of varieties. The modifications whose 

 origin is doubtful are simply oalled./orms. The modi- 

 fications will be indicated, when requisite, by a third 

 term, preceded, according to the case, by the words 

 variety, mutation, or form, or the corresponding 

 abbreviations. 



4. The specific name should always be precisely 

 designated by the indication of tlie name of the 

 author who established it. This author's name is to 

 be placed in parentheses when the primitive generic 

 name is not preserved; and in this case it is useful to 

 add the name of the author who changed the generic 

 name. The same disposition is applicable to varieties 

 elevated to the rank of species. 



5. The name attributed to each genus and to each 

 species is that under which it has been primarily 

 designated, provided tlie characters of the genus and 

 the species have been published and clearly defined. 



Priority will not be carried beyond Linn^'s Sys- 

 tema naturae, 12th edition, 1766. 



6. In future, for specific names, priority will be 

 irrevocably acquired only when the species shall have 

 been not only described, but figured. 



LETTERS TO THE EDITOR. 

 A po'werful direct vision spectroscope. 



At a journal meeting in wliich Professor Rowland 

 and the students of physics take part, an article came 

 tip for discussion which needs correction. In Comp- 

 tes rendus, April 9, 1883, Ch. V. Zenger, in a note 

 entitled ' Spectroscope h vision direct tres puissant,' 

 claims a dispersive power equal to that of thirteen 

 sulphide-of-carbon prisms of 60° angle for a spectro- 

 scope composed of a parallelepiped of two prisms, — 

 one of quartz, and the other of a mixture of ethyl 

 cinnamate and benzine, — combined with a third 

 prism of crown glass of angle of refraction 27° 1.3'. 

 He gives as the angles the three rays make with the 

 perpendicular to the last prism after they have passed 

 through, — 



A -90° 0' 



I) -55° 15' 



H +42° 55' 



It will be easily seen that JI should be negative in 

 place of positive; which will make the dispersion 

 between A and H 47° 5', in place of 132° 55' which 

 the writer gives. H. R. GooDNOW. 



Johns Hopkins university. 



Connecticut minerals. 



The towns of Middletown, Portland, Haddam, and 

 Chatham, in this state, have long been famed as a 

 region remarkable for the number of minerals occur- 

 ring in the veins of coarse granite. Within the last 

 few days two minerals have been discovered in these 

 veins, which, so far as I am aware, have not previ- 

 ously been reported. 



Torbernite has been found at Andrus' Quarry, 

 near the boundary between Portland and Glasten- 

 bury, associated with autunite, the occurrence of 

 which has been previously reported. 



Rhodonite has been found at the White Rocks in 

 Middletown. Wm. Nobth Rice. 



Book revieivs. 



I wish to quarrel a little with the critic of Gage's 

 ' Elements of physics ' in your issue of June 8, p.. 517, 

 for not keeping the following promise, found in the 

 'Prospectus of Science for 1883:' "To promote 

 one of its chief objects, and as a distinctive feature 

 of the journal, Science will give its hearty support 

 to those who are endeavoring to introduce the study 

 of the natural and physical sciences into public and 

 private schools, by drawing attention in every possi- 

 ble way to the high importance of this measure, as 

 well as by giving illustrated articles, plainly worded, 

 prepared by skilful hands, to guide the efforts of the 

 teachers." He has failed to keep this promise by 

 failing to give such information about the book he 

 reviews as " those who are endeavoring to introduce 

 the study of physical science into public and private 

 schools " would like to have. Many teachers cannot 

 afford to buy every text-book they see advertised, and 

 therefore must needs trust to reviews to tell them 

 enough of a book to enable them to decide whether 

 it is worth purchasing. In regard to a work on phys- 

 ics, they wish some such questions as the following 

 answered : — 



1. What is the plan of the book ? Does the au- 

 thor expect the pupils to do experimental work, or 

 that the teacher only will perform experiments ? 2. 

 If the author wrote with the view of having experi- 

 ments performed by the pupils, how well has he suc- 

 ceeded in executing his plan ? Has he succeeded in 

 giving such experiments as will be of real service 

 in laying the foundation of scientific work, and as 

 can be performed in the short time that teachers iu 

 high schools and academies have for such work ? 

 Could pupils manage the experiments without the 

 aid of a teacher ? 3. Does the author give any di- 

 rections in regard to preparing apparatus ? If so, 

 are these directions sufficiently exact and minute to 

 enable an inexperienced person to follow them with- 

 out trouble ? 



All of these questions a teacher would like to find 

 answered in the review of a new book on physics. 

 AH the information he would get on these points 

 from the review of Gage's book is found in this sen- 

 tence: "The book is of merit as giving many exper- 

 iments with apparatus of easy make." The reviewer 

 said more than this, of course ; but this one sentence 

 is all to answer such questions as I have asked above. 

 He was probably right in what he did say, which 

 makes it the more to be regretted that he did not go 

 farther. My quarrel with him is, that he did not say 

 enough ; that he did not say as much as your readers 

 had a right to expect, — certainly not enough for those 

 readers who had not seen the book, and wished to 

 know wliether it was worth buying. This suggests a 

 question. Are reviews written for the benefit of 



