1823.] Hoy al Society. 65 



place in the North Polar Distances of some of the principal feed 

 Stars ; by J. Pond, Esq. FRS. Astronomer Royal. .^ ; . , - 



On a Case oi Pneumato Thorax, in which the operation- of 

 tapping the chest was performed, with additional observations 

 on air found within the body, and on the absorption of air by 

 mucous membranes ; by J. Davy, MD. FRS. 



On the Length of the Invariable Pendulum in New South 

 Wales ; by Sir Thomas Brisbane, KCB. FRS. : communicated 

 by Capt. Kater, FRS. : in a letter to the President. 



Astronomical Observations made at Paramatta ; by Mr. Rum- 

 ker : communicated by Sir T. Brisbane, in a letter to the Presi- 

 dent. 



Of the Motions of the Eye, in Illustration of the Uses of the 

 Muscles of the Orbit; by Charles Bell, Esq. Part II.: commu- 

 nicated by the President. 



On Algebraic Transformation, as deducible from first Princi- 

 ples, and connected with continuous Approximation, and the 

 Theory of Finite and Fluxional Differences, 8cc. ; by W. G. Hor- 

 ner, Esq. : communicated by Davies Gilbert, Esq. Treas. RS. 



On the Apparent Magnetism of Metallic Titanium ; by Wj H, 

 WoUaston, MD. VPRS. 



In Dr. Wollaston's former paper on the minute cubes of metal- 

 lic titanium contained in the slag of the ironworks of Merthyr 

 Tydvil (see Philosophical Transactions for 1823, P^rt I. ; or 

 Annals of Pliilosophy for January last, p. 68), he had stated that 

 they were slightly magnetic ; for although they were not taken 

 up by a magnet, yet if one of them was suspended by a thread, 

 the action of the magnet would draw the thread upwards about 

 20°, indicating an attractive force equal to about one-third 

 of the weight of the crystal. By a comparative experiment, he 

 found that l-250th part of iron would impart equivalent magnetic 

 power to metallic substances, and by repeated solution and eva^ 

 poration, succeeded in removing so much of the titanium as to 

 discover, in the edges of the precipitate by tincture of galls, the 

 black colour of gallate of iron. It remains a question, therefore, 

 whether these cubes of titanium are properly magnetic them- 

 selves, or whether they derive their magnetism from the minute 

 portion of iron which they contain. 



An Account of the Effect of Mercurial Vapours on the Crew 

 of H. M.S. Triumph, in the year 1810; by William Burnett, 

 MD. : communicated by Matthew BaiUie, MD. FRS. 



Contributions towards a Natural and QEconomical History of 

 the Cocoa-nut Tree ; by H. Marshall, Esq. : communicated by 

 Sir James Macgregor, Bart. FRS, 



On the Diurnal Variation of the Horizontal Needle, w^hen 

 under the Influence of Magnets ; by S. H. Christie, Esq. MA. 

 Mem. Cam. Phil. Soc. and of the Royal Military Academy ; 

 communicated by the President. 



The President announced soniQ alterations iu the statutes of 

 'N&io Series, vol. vi. f 



