368 Geological Society, 



calculation, but we believe it to be the first expression which 

 has been given in terms of the sines, 



f, E _ — cosec s -f- cosec s— a -\- c osec .v— b -}- coscc s— c 

 2 — sins + s ' n *— a + sins— b ■+■ sin t"pe 



■j sin s sin s— a sins— b sins— c r s 



To some copies of this work Mr. Young has added a set of loga- 

 rithmic and other tables ; but as we have already occupied so much 

 of our space, we can only add that we like the arrangement of these 

 tables and certain contrivances employed in them very much. Of 

 their accuracy it is not easy to offer an opinion j but we feel it 

 proper to state that we have lately dipped into them, at hazard, 

 and with others of established reputation on our desk for compari- 

 son, about two hundred times, and in no one of these cases did we 

 detect an error. 



We hope, therefore, that the account we have been able to offer 

 of this unpretending work will have the effect — of calling the atten- 

 tion of younger students (and still more of professional tutors) 

 to it, as a book eminently calculated to ensure an early intimacy 

 with the practice as well as the principles of trigonometry, — and of 

 attracting the notice of geometers generally to the curious results 

 that appear in the supplemental chapters, and inducing them to 

 attempt the extension of a branch of science, which apparently 

 admits of almost unlimited cultivation. 



LXI. Proceedings of Learned Societies. 



GEOLOGICAL SOCIETY. 



May 15. — \ PAPER was first read entitled " Observations on 

 -£jL the Cliffs in the Neighbourhood of Harwich, made 

 in December 1832," by James Mitchell, Esq., LL.D., F.G.S. 



The principal object of this paper is to give a detailed de- 

 scription of the beds of London clay, as they appeared in the 

 Harwich cliffs at the time the author visited the spot. After point- 

 ing out the physical features of the line of coast, the effects which 

 the sea has produced upon the cliffs, and the means which have 

 been taken to defend them, he proceeds to give an enumera- 

 tion of the beds presented in a cliff which begins about 300 yards 

 to the south of the lighthouse, and extends for rather more than a 

 mile. 



The author next gives a description of the cement stone ; the 

 history of its first discovery by the late Rev. Dr. Parker in the year 

 1796; a list of the localities where it is found in the greatest abund- 

 ance ; then points out the difference between the cement stone of 

 Harwich and Sheppey, and lastly, advances an opinion on the pro- 

 bable period at which the supply will fail. 



"A Memoir on the Valley of the River Med way and the adjacent 

 Country," by R. Dadd, Esq., and communicated by James Mitchell, 

 Esq., F.G.S., was then read. 



The country described by the author lies in the immediate vicinity 



