276 



spending to this formula is also laid down, and its agreement with 

 the adjusted value placed in evidence. The author concludes with 

 some remarks on an error fallen into by Dr. Price, depending on the 

 periodical payment of interest ; and with a comparison of climacteric 

 years, as taken from different tables. 



Account of an Experiment on the Elasticity of Ice. By Benjamin 

 Bevan, Esq. In a Letter to Dr. Thomas Young, For. Sec. R.S. 

 Read April 27, 1826. [Phil. Trans. 1826, p. 304.] 



Mr. Bevan took the opportunity of the severe frost of the last 

 winter to determine the modulus of elasticity of ice, which he did by 

 cutting a rectangular plate of that substance from the surface of a 

 pond of 100 inches in length, 10 in width, and about 4 in thickness. 

 The deflection produced by a weight of 25 Ibs. was 0*206 inches, 

 from which he concludes the modulus of elasticity to be 2,100,000 

 feet. 



The modulus for water he states at 2,178,000 feet, on a certain 

 hypothesis respecting its cubical compression. 



Results of the Application of Captain Kater's Floating Collimator to 

 the Astronomical Circle at the Observatory of Trinity College, Dub- 

 lin; and Remarks relative to those Results. By theRev. J. Brinkley, 

 D.D. F.R.S. P.R.I.A. Communicated by the Board of Longitude 

 February 2, 1826. Read April 27, 1826. [Phil. Trans. 1826, 

 p. 307.] 



Dr. Brinkley, in this communication, states a number of observa- 

 tions made with the floating collimator of Captain Kater, as applied 

 to the Dublin circle, in which he observes it affords the means of 

 ascertaining the index error with as great precision as by reversion, 

 and that in several points of view it is undoubtedly superior to that 

 method. The reversing principle of the Dublin circle, he observes, 

 serves very conveniently for a measure of the accuracy of the float- 

 ing collimator, and serves to show very satisfactorily, that applying 

 this instrument to any circle will introduce no error depending on 

 the collimator itself. 



The author regards the results of these observations as highly 

 favourable to the principle of the collimator, which he considers as 

 a new astronomical power, and as even belonging to a more ad- 

 vanced era of practical astronomy than the present. 



The observations consist of, First, the mean zenith distances of a 

 number of stars, deduced solely by the application of the index cor- 

 rection, as determined by the collimator. In this case the circle was 

 used as a mural circle, or rather as two mural circles, having been 

 used with its face east and also west. Secondly, the inclination of 

 the line of collimation of the collimator, as determined on different 

 days. As this appears to have been very permanent (though such 

 permanence is not essential in practice), he concludes that the 

 collimator is applicable to the most powerful instruments. Thirdly, 



