June 9, 1893.J 



SCIENCE. 



311 



trutn taken for measurement, which we will call the unit of the 

 color, a patcli of the spectrum obtained by a diffraction grating, 

 representing a range of fifty ten-millionths of a millimetre in 

 wave-length, was selected. This gives an area of color of con- 

 venient size for comparison, and one which appears quite homo- 

 geneous to the eye, even in those parts of the spectrum where the 

 change is most rapid. The wave-lengths here given represent 

 the centre of the area selected. The location of the standards 

 with relation to the absorption lines of the spectrum, where such 

 a location was possible, will give a convenient means of ascer- 

 taining the position of the standards I have selected without 

 recourse to the elaborate method required in the use of the 

 goniometer. 



The Standard Spectrum Colors. 



To obtain the intermediate hues, which it may seem desirable 

 to introduce between these standards, these should be combined 

 in inverse proportion to what the artists call the " value" of the 

 colors. This is not, perhaps, easily determined, yet its approxi- 

 mate measure can be ascertained with sufficient accuracy for this 

 purpose. These, however, are of much less consequence than the 

 standards. Using Maxwell discs in these standards, the following 

 formulae will serve to illustrate, viz. : — 



Orange Red R 70, 30, Red Orange R 41, 59. 



Here the orange, having what the artist calls a higher " value," 

 is used in a smaller proportion than the red. The same will be 

 true in producing the tints and shades of any color. The amount 

 of white or black to be used must be determined by the value of 

 the color. 



It has been urged in objection to the spectrum colors that they 

 are not the colors of nature. In reply to this objection, it should 

 be said that nature has no other colors than those of the spectrum. 

 With these, however, are combined more or less of white light and 

 shadow, producing the beautiful effects which so charm us in the 

 landscape as it is spread out before us. For purposes of instruc- 

 tion, a series of what we may call 'broken" colors is valuable. 

 These are mixtures of the standards with both white and black, 

 in given proportions. The amount of white and black must be 

 determined, as in the case of tints and shades, by the value of the 

 color. For advanced educational purposes, these broken colors 

 are valuable, but should not be used until the student is well 

 grounded in the knowledge and use of the standards. 



The adoption of this scheme for practical purposes is also a 

 subject of interest. By the use of the Maxwell discs, made in 

 these standard colors, it is possible to determine the components 

 of any color with which one may meet. The formula for sucb an 

 analysis will enable anyone, by means of a similar set of discs, to 

 reproduce the color with perfect ease. New combinations of 

 color may also be produced with equal facility. In cases of ex- 

 perimentation, to ascertain what combinations of color would be 

 harmonious, this is a great saving of time, labor, and cost. 



The use of such terms as vermilion, emerald green, ultramarine, 

 and other similar terms to express the results of analysis, is im- 

 practicable in the extreme, on account of the variability in the use 

 of the terms. 



Discs made in these standards are manufactured and can be 

 furnished at a moderate price. These discs are at present made 

 in pigments, which are excellent reproductions of the spectrum 

 hues. Some of them, however, can be produced in the brilliancy 

 required only by the use of analine colors, and these are not 



permanent when exposed to the light. For this reason they 

 must be carefully protected when not in use and have to be fre- 

 quently renewed. 



MISSOURI OFFICIAL GEOLOGICAL REPORTS. 



BY F. A. SAMPSON, SEDALIA, MO. 



The late publications of the geological survey of Missouri con- 

 tain lists of the reports of the survey, which lists are not complete 

 and give but a part of the official geological reports of the State; 

 the four below mentioned should clearly be added to the list. 



By an act of the legislature of the State approved Feb. 11, 

 If 39, a Board of Internal Improvements was organized to have 

 supervision and control over all State roads, railroads, slack- 

 water navigation, or canals. The act provided for the appoint- 

 ment of a chief engineer, who should cause to be compiled " a 

 large and correct map of the State" showing in " a correct and 

 minute manner" the geographical, topographical, and geological 

 features of the State. In his office should be kept "all reports 

 of engineers, geologists, and other scientific persons, either con- 

 tributed by individuals or ordered by the State." A supplemen- 

 tal act, dated two days later, provided for surveys of four rivers, 

 the Osage, the North Grand, the Salt, and the Merrimac, and 

 one railroad route, that from St. Louis to the Iron Mountain. 



The members of the board were appointed by the Governor, 

 and these were assigned as commissioners of the above five 

 roul:es. A State engineer and a geologist of the Osage River 

 survey were also appointed. The journal of the board and the 

 reports of the chief-engineer and geologist are among the scarcest 

 of the publications of the State. I know of no copy in the State 

 except my own. It was ijublished in the appendix to the Senate 

 journal of the eleventh General Assembly, 1840-41, and probably 

 in the House journal also, but I have never seen any copy of the 

 latter, I know of no copy of either journal in any library in the 

 State. The report I have I found in the tower of a court-house 

 in Central Missouri, the journal part having been torn away, but 

 leaving the appendix complete. The title of the report is " Re- 

 port of a Geological Keconnoissance of that part of the Slate of 

 Missouri adjacent to the Osage River, made to William H. Mor- 

 rell, Chief-Engineer of the State, by order of the Board of Inter- 

 nal Improvement, by Henry King, M.D. , Geologist, President of 

 the Western Academy of Natural Sciences, etc., etc.," pp. 506- 

 525. 



Professor Swallow made a report on the southwestern branch, 

 in obedience to the act of March 3, 1857, which required the 

 State geologist to make a thorough survey along the lines of all 

 railroads aided by the State, and to report in detail to the presi- 

 dent and directors "all the mineral, agricultural, and other re- 

 sources which may affect the value or income of the road under 

 their direction." But one such report was published, but this is 

 as much one of the official reports of the survey as any other of 

 Swallow's reports. Its title is "Geological Report of the Coun- 

 try along the line of the Southwestern Branch of the Pacific 

 Railroad, State of Missouri. By G. C. Swallovc. State Geologist. 

 To which is prefixed a Memoir of the Pacific Railroad. St. 

 Louis: Printed by George Knapp & Co., 1859." 93 pp., plates 

 and geological map of southwest Missouri. 



Another edition of this report somewhat fuller was published 

 in New York by the Pacific Railroad Company, but I have not 

 seen a copy of it. 



The third omitted report is a short one, but it could not have 

 been omitted on account of that fact, as Swallow's third report 

 is still shorter. It is entitled as follows: "Report to the Board 

 of Curators concerning the Transfer of the Geological Survey to 

 the School of Mines, and the work executed during the year. 

 By Charles P. Williams, Ph.D., Director Missouri School of 

 Mines and Acting State Geologist." 



When preparing the bibliography of the geology of Missouri I 

 found this report in the catalogue of the Missouri State Univer- 

 sity for 1876, pp. 313-216, a publication in which one would not 

 look for a geological report, but for some years the catalogues of 

 the university contained many papers of merit, as addresses and 



