Intelligence and Miscellanies. 197 



tain cases. It should have been expressed, [and suppose DFME 

 to be another similar to it,] Although all right lines, termina- 

 ted by corresponding points in curves which are similar, are 

 parallel ; yet the curves themselves may not be parallel, as will 

 appear evident upon a little reflection. For instance, two ellip- 

 ses, that are similar, are not parallel. The subsequent train of 

 reasoning, however, is not aifected by this inaccuracy. The N. 

 B. at the close of the theory may, I think, be more fully and ac- 

 curately expressed thus : The projection is made by rays paral- 

 lel to a line drawn from the nearest corner at the left hand at the 

 top, diagonallj, to the furthermost corner at the right hand at the 

 bottom. The sides GHFE in tig. 2. and L-ON in fig. 6. stand 

 on the plane of projection ; and the opposite sides CDBA in tig, 

 2. and AKMF in tig. 6. are elevated. The sides ABFE in fig. 2. 

 and PMON in fig. 6. front the reader. The sides GCAE in fig. 2. 

 and LAPN in fig. 6. are situated on the left hand. The other 

 sides, in the projection, fall behind and are hidden. The reader 

 will notice that the position of the cube in fig, 6. is different from 

 tiiat in fig, 2. as is denoted by the letters. That the little blue 

 cuibe in fig. 6. may be brought into view, the original cube is 

 turned about, so that the side ABFE, which in fig. 2. fronts the 

 reader, in fig 6, falls on the left hand side. E. W. 



6. Errors corrected in Dr. Robinson'' s Catalogue of Minerals. — ■ 

 The localities mentioned in this manual, are, in many cases, 

 not described with adequate particularity. The township 

 is mentioned, but not the particular spot in which the min- 

 eral occurs. The traveller sometimes spends hours, and even 

 days, in a fruitless search after it. Perhaps this marked defi- 

 ciency was unavoidable. The compiler copied most of his lo- 

 calities from the public journals, where the same defect exists, 

 and must have been observed by all who attentively read them. 



There is another fault to be noticed. It is common to the cat- 

 alogue, and to the journals. An individual discovers an interes- 

 ting mineral — a small mass of fluate of lime, or lepidolite, or 

 rose-quartz, and takes the whole, to his own cabinet, and then, 

 publishes the locality; those who come afterwards, are of course 

 disappointed, as the substance is not to be found in that region. 



Localities of minerals should never be named in our public 

 journals, without a statement of the quantity. This precaution 

 would save much exertion, now thrown away. 



The catalogue contains a number of errors.^ which are now 

 making their appearance and circulating in other works, in 

 our country. Two or three of these mis-statements, those 

 with which my name is coupled — I will point out ; and you, 

 Sir, will do me a favor, by giviog this paper a place in your 



