Solar Eclipse 0/ Juii/ 28, 1851. 86 



trusted that many English travellers might be induced to 

 observe this eclipse. If possible, stations should be chosen 

 as well near the northern and southern boundaries of the 

 shadow as near the centre. No particular skill in astronom ical 

 observation is required, the phenomena being rather of a more 

 generally physical kind : and indeed, as far as the observa- 

 tions of the eclipse of 1842 shewed, the travelling physicists 

 had been more successful than the stationary astronomers. 

 The apparatus required would depend on the special objects 

 of the observer ; a telescope and a watch might be considered 

 indispensable in every case : for analysis of light, a common 

 prism and a polariscope might be taken by some persons : 

 photometry, actinometry, &c., might be interesting to others, 

 and appropriate instruments would be required : other ob- 

 servers would be interested in meteorology. The apparatus 

 which the Lecturer considered it most important to perfec- 

 tionate now, for use during the eclipse, is photogenic appa- 

 ratus ; it would be impossible to set too high a value on a 

 series of Daguerreotypes or Talbotypes of the sun and corona 

 taken during the eclipse. 



The Lecturer concluded by saying that a series of sugges- 

 tions for the observation, accompanied by a map, had been 

 prepared by a Committee of which he is a member, and were 

 nearly ready to leave the printer's hands : and he undertook 

 to transmit a copy of these suggestions to any person who 

 would make application to him.* 



On the Composition of Nullipores and some Corallines. By M. 



Damour. 



The author submits to the Academy the result of researches which 

 he commenced last year on the composition of certain marine or- 

 ganised bodies, known by the name of Nullipores. These marine 

 productions, now classed with the Algae, at first sight resemble 

 mineral concretions. They assume various forms ; sometimes that 



* We refer our readers, for observations made during the Annular Solar 

 Eclipse on the 15th of May 1836, at Edinburgh and the neighbourhood, by 

 Captain Alexander Milne, R.N. (one of the present Lords of the Admiralty), 

 and the astronomers, Galbraith and Sang, inserted in vol. xxi. of this Journal. 

 —Edit, of Ed. N. Phil. Jtournal. 



