Scientific Intelligence. — "Mineralogy. 416'' 



vail with regard to the tides of the Mediterranean. In the article' 

 on '* Physical Geograpliy," in the Encyclopaedia Britannica, it is 

 stated, that ** tides are but little felt in the Mediterranean, seldom 

 rising to six inches above the mean level," and that they are •• irre- 

 gular." I believe the idea is very general that no tide occurs in that 

 sea, but I ascertained, by a series of observations I made at the an- 

 cient port of Antium, on the coast of the Roman states, in the sum- 

 mer of 1836, that the tides ^vq perfectly regular; and the rise amount- 

 ed there to about fourteen inches. In the more eastern parts of the 

 Mediterranean, they are, I believe, shewn by some of the recent sur- 

 veys (to which I have not had an opportunity of referring), to be 

 much greater, though in the extreme west they are probably scarcely 

 sensible, as observed in the article on Physical Geography, though 

 the remark appears there to be erroneously applied to the whole 

 of that sea. 



In the narrow Adriatic, the tides are, of course, larger than in the 

 Mediterranean ; they appear to have been well known to the ancients, 

 and, in more modern times, have been satisfactorily investigated by 

 Dr Bianchi of Rimini, whose work * is for the number and accuracy 

 of the observations, quite worthy of a philosopher of the present day. 

 He proves not only the regularity of the tides in that sea, but their 

 rise to nearly four feet (English) at new and full moon, and half that 

 amount at neap-tides. The observations of Galileo must be familiar 

 to many of your readers ; he ascertained the difference between high 

 and low water at Venice, to amount to as much as six or seven feet 

 (English), and he also observed that there were tides in the Mediter- 

 ranean. — W. C. Trevelyan. 



MINERALOGY. 



6. Hydrargillitey a new mineral species. \ — Description. Colour 

 reddish-white ; occurs crystallized in crystals belonging to the rhom- 

 bohedral system ; the forms are the six-sided prism, feebly trun- 

 cated on the lateral edges by the faces of the second six-sided prism. 

 The faces of the first six-sided prisms are feebly longitudinally 

 streaked, the other faces smooth. The crystals are perfectly cleav- 

 ablo in the direction of the terminal faces. Lustre on the terminal 

 faces .splendent and pearly, on the other faces shining and vitreous, 

 and least on the faces of the first six-sided prism. Translucent, but 

 transparent in thin folia. Hardness, examined by means of the file, 

 appears less than that of calcareous spar, but the different fiices vary 

 in hardness, for the straight terminal faces are easily scratched by 



* " Jani Planci Ariminenisis de Conchis minus notis liber. Cui accessit 

 speciiuen sestus reciproci maris superi ad Littus Portumque Arimini. Edi- 

 tio altera, Roma) 17(iO," 4to. James Plancus was a name assumed by Dr 

 Bianclii, in accordjince, I believe, Avitli the custom of the members of the 

 Lynca>an Academy, of whom he was one of the most active, about the 

 middle of last century. 



t This and several of the following mineralogical notices arc prepared 

 from Poggmdorff''s AwnaUn^ — Edit, 



