276 Mr. H. Tomlinson. The Influence of [Jan. 26, 



it were derived by interpolation from the wave-lengths of the magne- 

 sium and iron lines. The arc of a De Meritens machine taken in a 

 crucible of magnesia gave us, when a current of steam was passed 

 into the crucible, both the water spectrum and the metallic lines on 

 the same plate. The solar lines are marked in the figure in positions 

 held by the corresponding iron lines. These photographs were taken 

 with prisms of Iceland spar. None of our photographs show any 

 more refrangible rays produced by water within the limit of trans- 

 parency of Iceland spar, i.e., below a wave-length of about 2200. 



III. " An Attempt at a Complete Osteology of Hypsilophodon 

 Foxii, a British Wealden Dinosaur." By J. W. Hulke, 

 F.R.S. Received January 16, 1882. 



(Abstract.) 



The author, after giving a list of papers on remains of this Dinosaur, 

 by Professor Owen, Professor Huxley, and himself, and noticing the 

 great want of a complete osteology which might serve as a type, 

 describes in detail the skull, including the dentition, the vertebral 

 column, shoulder- girdle, and hip-girdle with the limbs, and compares 

 their structure with that of other fossil and extant Sauropsida. He 

 maintains the generic distinctness of Hypsilophodon from Iguanodon as 

 typified by I. Mantelli, considering that the very different structure of 

 their hind feet is decisive of this. The paper embodies the results of 

 dissections of parts of several skeletons, and it is illustrated by figures 

 of all the bones described. 



IV. Ci The Influence of Stress and Strain on the Action of Phy- 

 sical Forces." By Herbert Tomlinson, B.A. Commu- 

 nicated by Professor W. Grylls Adams, M.A., F.R.S. 

 Received January 18, 1882. 



(Abstract.) 



Part II.: — Electrical Conductivity. 

 The temporary alteration of electrical cond activity which can be 

 produced by longitudinal traction was measured for all the metal 

 wires used in Part I, both in the hard-drawn and annealed condition, 

 and, in addition, for carbon and nickel, by the following method : — 

 The wires were suspended in pairs of equal lengths in an air-chamber 

 ■4 feet in length and 4 inches inner diameter. This vessel, which 

 consisted of two concentric cylinders containing a layer of water 



