148 Scientific Intelligence. 
There are many cases in which difficulty may be occasioned by in- 
attention to the kind of consideration we here advert to. In the case 
before us, a clear distinction is observable between AD considered as a 
limit of the lines which meet FG produced, and AD considered as the 
limit of those lines which do not meet FG produced. In the former 
case, the line AD belongs not to the class of lines limited by it, while 
in the latter, it is one of that class of lines which it limits. At the bot- 
tom of page 95, this important distinction is disregarded, when it is said 
that if AD is contained by BAD, it must meet FG or FG produced. 
Further objections to the demonstration under notice, similar to those 
here suggested, might be advanced ; but if the consideration which has 
been referred to be kept in view, they will readily occur to the reader. 
A. D. 
BIBLIOGRAPHY. 
1. Notice of Mr. Aucer’s Pxiuutrs’ Mineralogy.—Prof. Gustav 
Leonuakp of Heidelberg, Germany, has givena very favorable notice 
of Mr. Aucer’s book, (already reviewed in this Journal.) It appears 
‘nthe Annalsof the University of Heidelberg, and we abstract from it 
the following:— . 
“ The fifth edition of a work is the best encomium upon its character, 
especially of one of a scientific nature. The first four editions of 
Puiturs’s work appeared in London; the fifth has now been published 
in Boston, edited by Mr. Anger, whose name was previously adyan- 
tageously known by his beautiful investigations in Nova Scotia, and by 
the Essay which he published thereupon in common with Dr. Jackson. 
It was but very recently that we had occasion to allude in these pages 
to the scientific activity that reigns in the United States ; and this work 
of Mr. Aucrr furnishes us with additional proof thereof. The Miner- 
‘alogy of Puituips appears in a new dress, much improved and aug 
mented. The minerals are arranged according to a chemical sys- 
tem. The most satisfactory and accurate analyses are given for each 
species, and there are additional analyses by Dr. Jackson and oth-— 
ers, of American minerals, as Danaite, Cavanite, Hudsonite, Mason- 
ite, and Ledererite. The figures of the crystals, amounting 0 
are admirable, and there is much interesting information tou hing the 
occurrence of minerals, those of Nova Scotia and South America in 
particular. There is no doubt in our mind that Mr. Ancer’s Mineral- 
ogy, splendid as it is in its getting up, will find many readers. It is 
peculiarly adapted as a compendium for students.” 
2 Die Metcoriten, or Meteorites in the Imperial Mineral Cabinet at 
Vienna; by Pavt Parrscu. pp. 162, 8vo, with a plate. Vienna, 1843. 
—The Vienna cabinet of meteorites contains two hundred and fifty 
