163 



three species of marine Zoophytes, was also read. These are three 

 new species of corallines of the genera Coppinia (Hassall, ' Zoologist,' 

 No. 69, p. 2223), Sertularia, and Cainpanularia. They are respec- 

 tively named Coppinia mirabilis, Sertularia gracilis, and Campanularia 

 serpens, and are found on the English and Irish coasts. Detailed 

 descriptions were given, and drawings exhibited in illustration of the 

 same. 



A third paper, being a translation of a letter from M. Nobert, giving 

 a description of a glass plate, having on it twelve systems of parallel 

 lines, was read. These systems of lines were distinguished by the 

 letters A, B, and C, to M. the latter being the finest; and the dis- 

 tances in each set were expressed with the most scrupulous exact- 

 ness in Paris lines, as being, in system A, 0."'000375 to system M, 

 which was the finest, 0."'0001281. The other systems were of inter- 

 mediate degrees of fineness. By using this plate in a particular man- 

 ner, fully described in the paper, the systems of lines from A to G 

 present an aerial spectrum of the prismatic colours, A being deep i-ed 

 and G a deep violet ; and as no colour appears in the remaining sys- 

 tems (from H to M), the author considers that the distance of the lines 

 in these systems is nearer than the length of the smallest (the violet) 

 undulations of light. Upon turning the plate, and arranging it in a 

 rather different manner, coloured representations of the whole of the 

 twelve systems are produced, not, as in the former instance, in the air, 

 but in the glass; and npon comparing these with the aerial spectrum, 

 it is found that the colour of the system F, being deep red, agrees with 

 that of A in the aerial spectrum G, with B, and in like manner the fol- 

 lowing systems, H, 1, K, L, M, with those of the former, C, D, E, F, 

 G ; and by uniting the numerical values for the distances of the lines 

 harmonizing in their colours, the main result is, that the length of the 

 undulations in the glass is in proportion to that of those in the air, as 

 1 to 1.53, furnishing a direct confirmation of the truth of the undu- 

 latory theory. The correctness of these results was also stated to 

 depend on the absolute accuracy of the distances of the lines, as an 

 error of only ^^-oWot^h of 3- Paris line was found to produce stripes of 

 other colours, and if the distance of the lines in system M (that which 

 produces the violet rays in the glass spectrum) is diminished by only 

 3^'^th of that amount, the colour will entirely disappear. — J. W. 



