Physics and Astronomy. 239 



SCIENTIFIC INTELLIGENCE. 



I. Physics and Astkonomy. 



1. The Variation in the Density of Water with the Tempera- 

 ture. — D. Mendeleeff in an exhaustive paper discusses the 

 results of previous observers, and points out that the formula 



(f 4)3 



S, = 1 — , K w „ — v^r obtained by him appears to embrace all 

 ' (A + t)(B — t)C 3 rr 



that is known of the variations of the density of water between 

 — 10° C. and 200° C. with the accuracy that is now attainable. 

 He points out that if fresh determinations of greater accuracy 

 should confirm the accuracy of this formula, or lead to a more 

 correct formula, we may hope to arrive at a better understanding 

 of the true law of the expansion of all liquids and also of gases. 

 By means of investigations upon water we may hope to make 

 further progress in the study of matter under the influence of 

 rise of temperature. — Phil. Mag., Jan., 1892, pp. 99-132. j. t. 



2. On a New Method of obtaining a Constant Temperature. 

 — Mr. Henry Clew has employed an electrical current in the 

 following manner. The current from a certain number of storage 

 cells is led through a fine covered wire of high specific resistance, 

 which is coiled about the glass vessel in which the temperature is 

 to be maintained. The glass vessel is contained in a suitable 

 calorimeter. In one experiment the temperature was maintained 

 constant within y^ of a degree for 40 minutes and the author 

 believes that much greater constancy can be obtained. — Phil. 

 Mag., Jan., 1892, p. 89-93. j. t. 



3. Velocity of Sound in membranous bodies. — L. Melde has 

 obtained the velocity of sound in membranes of various natures 



.by taking strips of the membranes. These were fastened at both 

 ends and were rubbed in the middle. A table of the results is 

 given and shows a great difference in the propagation of sound in 

 various substances. — Beiblatter, Ann. der Physik und Chemie, 

 No. 11, 1891, p. 756. j. t. 



4. A Surface Bolometer. — At a meeting of the Physical 

 Society held in Berlin, Jan. 8, Dr. Kurlbaum described a surface 

 bolometer. It is cut out of platinum foil whose thickness is 

 0*012 mm. and possesses the great advantage of coming to rest 

 quickly. It is a trustworthy instrument for measuring the dif- 

 ference in luminositv of two sources of light. — Nature, Jan. 28, 

 1892. j. t. 



5. Orthochromatic Photography. — MM. Fabre and Andoter 

 photographed the eclipsed moon at the Toulouse Observatory on 

 Nov. 13, 1891. They employed collodion-bromide and collodion- 

 chloride plates which were stained either with eosin or cyanine. 

 The collodion bromide plates were relatively more sensitive to 

 red and yellow than the collodion-chloride plates. — Nature, Jan. 

 21, 1892. j. t. 



