358 



SCIENCE 



[N. S. Vol. LIV. No. 1398 



detailed report of operations will be made 

 public as soon as practicable. 



Jay L. B. Taylor 



PiNEVILLE, Mo. 



SOME SUGGESTIONS FOR PHOTOGRAPHING 

 FOSSILS 



For some time the writer, when photograph- 

 ing fossils, has used the whitening process con- 

 tributed by Professor S. H. Williams, but, 

 with many others, he has found it not al- 

 together satisfactory. In order that the 

 whitened specimen should contrast with a 

 white background it has been necessary to 

 over-expose or over-develop the prints. Be- 

 cause of this, many of the minor details of fos- 

 sils , have been lost in reproduction, and the 

 pictures, as a rule, have seemed flat and " life- 

 less." In addition, it is usually the practise 

 to opaque the background of the negative as an 

 aid in determining how far to carry the de- 

 velopment of the print. This process is pains- 

 taking and slow at best. 



Some time ago, the writer, with the assis- 

 tance of Mr. Parke Bryan, developed a slight 

 variation in the photographing of whitened 

 fossils that seems to be a decided improve- 

 ment. The time required is materially short- 

 ened, in that the negative requires no 

 opaquing, and the results are so gratifying in 

 the way of improved reproductions that it 

 seems worth while to outline briefly the 

 method. 



The method is a combination of the com- 

 mon lighting arrangement used in portrait 

 photography, and the whitening process of 

 Professor Williams. The specimen is mounted 

 on a slender stick with modeling clay and then 

 coated with a thin film of white. A dull white 

 background, placed some distance behind the 

 specimen, is turned at an angle such that it 

 receives the full light but does not reflect it 

 toward the camera. After the photographing 

 table is orientated so as to give the conven- 

 tional light direction and the desired light- 

 shade contrast to the relief features, a screen 

 is placed between the specimen and the source 

 of light so as to intercept the direct rays. The 

 screen consists of one or more thicknesses of 



cheesecloth sewed on a wire frame, the num- 

 ber of thicknesses depending on the intensity 

 of the light. Every feature of the fossil now 

 shows clearly on the ground glass of the 

 camera, although the specimen appears dark 

 against a pure white back. 



It has been found that the shadows on the 

 under side and away from the light source are 

 more intense than the image on the ground 

 glass indicates, and except in the case of rela- 

 tively flat specimens it has been necessary to 

 use a slight back reflection. A sheet of dull 

 finish white cardboard held at the proper 

 angle has in every case been sufB.cient for this 

 purpose. If an actinometer is used to deter- 

 mine the time of exposure, it is obviously the 

 light of the shaded specimen that is to be 

 tested. 



Maurice G. Mehl 



Department of Geology, 

 "University of Missouri 



SCIENTIFIC BOOKS 



Vitamines: Essential Food Factors. By Ben- 

 jamin Harrow, Ph.D. !N"ew York, E. P. 

 Button & Co., 1921. Pp. 219. Price $2.50. 

 The author of this book has been at great 

 pains to popularize a subject which the laity 

 will certainly be glad to have so clearly pre- 

 sented. About half the volume is prelimin- 

 ary to the specific topic; it is a general 

 account of nutrition and the story is well 

 told. One is disposed to wonder whether 

 readers who require such a very elementary 

 introduction will appreciate the later chap- 

 ters which are of necessity more difficult. 

 However, a rare degree of order and sim- 

 plicity is maintained to the end. The writer 

 has a judicial attitude; he does not assert 

 opinions of his own but quotes others with 

 fairness and has evidently been in corre- 

 spondence with the leading investigators that 

 he may accurately express their views. 



Of course not much space can be devoted 

 to controverted matters in a book of this 

 character. But a dogmatic tone is avoided. 

 It should be plain to the reader that many 

 problems await solution. Among the ques- 

 tions not fully settled may be mentioned the 



