16d Mounilng of Naval Ordnance, 



Quarterly Journal of Science, we have shown from the ana- 

 lysis of facts to be as perfectly practicable as it is desirable ; 

 and it is to be hoped that other maritime powers will not be 

 the ^rs^ to derive the advantages of an invention, whose dis- 

 cussion has not only thrown a new light on the badly under- 

 stood subject of naval gunnery, but is in itself so well calcu- 

 lated to produce a great simplicity and facility in some of its 

 operations — operations which have hitherto been to a degree 

 complicated and laborious ; and, what is still worse, eminently 

 deficient in effecting their purposes. , j. 



We cannot take leave of Commander Marshall's work 

 without expressing our conviction that all professional men 

 of science will set that value on its contents which true 

 reasoning will always command ; and we are fully persuaded, 

 that, with a " fair field and no favour,'" his system of mount- 

 ing naval ordnance will be found to excel all other systems as 

 much in practice as it does in principle. 



On Indigo. By Andrew Ure, M.D., F.R.S., &c. 



Among the vast variety of vegetable products, there is probably 

 none so interesting to science, by the curious complexity of its 

 nature, and the protean shapes it may be made to assume, as 

 indigo; and, certainly, there are few more important to British 

 commerce and enterprise, since it constitutes the most valuable 

 article of export and remittance from Hindostan. At the four 

 quarterly sales appointed by the East India Company, no less 

 than twenty thousand chests of this dyeing drug are, on an 

 average, brought annually into the market. A very consider- 

 able quantity of indigo is also imported into Europe from Ame- 

 rica and Egypt. It is not long since the Caraca and Guatimala 

 indigo held a much higher character, and commanded a much 

 better price than that of India ; but the improvements due to 

 the intelligence of our planters in the East have, within these 

 few years, enabled them to prepare an article very superior to 

 the finest American. The sequel of this paper will present 

 satisfactory proofs of this assertion. 



Indigo is procured from many different species of plants, 

 belonging to Tournefort's natural family of leguminous, in- 

 cluded for the most part in the genus called indigofera by 

 Linnaeus. According to Heyne, the indigofera pseudo'tinctoria 



