Mabch 14, 1919] 



SCIENCE 



265 



power to aid in this accomplishment by in- 

 ducing institutions which they can influence 

 to subscribe. All correspondence relating to 

 subscriptions should be addressed to M. G. 

 Severin, ilusce Royal d'llistoire Naturelle, 

 31 Eue Vautier, Bruxelles, Belgium. 



Philip P. Calvert 

 UNrTEKSiTT OP Pennsylvania 



CROSS-SECTION LINES ON BLACKBOARDS AND 

 THEIR ILLUMINATION 



Those who wish cross-section rulings on 

 blackboards temporarily, thus leaving the 

 board free for other work after the curve-plot- 

 ting is finished, can do so by a simple device. 

 On a sheet of white paper make a ruling of 

 lines, 2 cm. apart, the whole grid being 16 X 24 

 cm., and the lines not quite one mm. thick. 

 Take a photograph of this, making the camera 

 image the size of a lantern-slide. Mount the 

 negative in a lantern, projecting the image on 

 the blackboard. A lantern equipped with a 

 400-watt Mazda lamp wiU make the lines suffi- 

 ciently visible for plotting even in a well- 

 lighted room. The lines are erased by turn- 

 ing off the lamp. 



FLOOD-LIGHTING FOR BLACKBOARDS 



A SIMPLE system of lights should be added in 

 dark recitation and lecture rooms, so that no 

 light reaches the eye, either from the illumi- 

 nant, nor from the board by direct reflection. 

 A 40-watt lamp suffices for 4 ft. of blackboard, 

 and need not project from the wall more than 

 18 inches. 



Paul F. Gaehr 



Wells College 



concerning the manufacture of 



SULPHONIC ACIDS 



The Department of Agriculture announces 

 that the color laboratory of the Bureau of 

 Chemistry, of this department, has developed, 

 on a laboratory scale, a new process for the 

 manufacture of certain sulphonic acids. This 

 process, as carried out in the laboratories, ap- 

 pears so promising that it is thought that some 

 manufacturers of chemicals and dyestuffs in 

 this country may be able to supply their de- 

 mands for these and other valuable compounds 



by this process, provided the process can be 

 reproduced upon a technical scale so as to 

 obtain results commensurate with laboratory 

 investigations. The process refers particularly 

 to the sulphonation in the vapor phase of ben- 

 zene, naphthalene, and other hydrocarbons. 



With a view to helping the chemical in- 

 dustry of this country, the Department of 

 Agriculture hereby announces that it is ready 

 to assist manufacturers who wish to produce 

 these compounds. The expenses of the tech- 

 nical installation and of the labor and mate- 

 rials necessary will of necessity be borne by 

 the firm, individual, or corporation wishing to 

 manufacture the products. The chemists of 

 the Color Laboratory will assist with expert 

 advice, etc. The department reserves the right 

 to publish all the data obtained from the tech- 

 nical experiments. 



This offer of assistance will not be held open 

 by the department for an indefinite period. 

 D. F. Houston, 

 Secretary 



Depabtment op Ageiculture, 

 Washington, D. C. 



SCIENTIFIC BOOKS 



British Antarctic (Terra Nova) Expedition, 

 1910. Natural History Eeport, Zoology, 11., 

 N"o. 8. Brachiopoda. By J. Wilfrid Jack- 

 son, F.G.S. 4to, pp. 177-202, 1 pi., July 27, 

 1918, London, British Museimo. 

 The various Antarctic expeditions in the 

 years immediately preceding the war, obtained 

 material greatly extending our knowledge of 

 the fauna of the regions about the Southern 

 Pole. This to a considerable extent reached 

 tlie scientific world by means of publication, 

 but a certain portion was delayed and, owing 

 to war conditions, seemed likely indefinitely 

 to continue so. It is therefore with peculiar 

 pleasure that we have received the present con- 

 tribution issued during the past summer by 

 the trustees of the British Museum. 



The Brachiopoda obtained by the Terra Nova 

 party form an interesting and valuable series 

 adding considerably to our knowledge of the 

 characteristics and geographical distribution 

 of the Antarctic species. One of the forms 



