210 Miscellanies. 



and is very pure. The column rises from a source one third of a mile 

 below ground, and it spouts thirty feet above the surface. The tempera- 

 ture at the bottom of the boring* was nearly 83° of Fahrenhefit, (that of a 

 hot summer's day, such as is rarely known there on the surface,) thus 

 confirming fully the increase of heat in the interior of the earth, by 

 the average generally observed in similar cases of about 1° for fifty feet 

 of descent, which, at the same rate of increase, would give a fountain of 

 boiling water at two miles from the surface — full ignJtion of rocks at ten 

 miles, and fusion at two hundred miles ; thus leaving a firm crust to pre- 

 serve the good citizens of Paris from being disturbed by the fear of 

 breaking through, or by the danger of the immediate outburst of the fire. 



20. The Theory of Horticulture : or an attempt to explain the princi- 

 pal operations of Gardening upon Physiological Principles ; by John 

 LiNDLEV, Ph. D. F. R. S., &c. &c. First American edition, with notes, 

 &c., by A. J. Downing and A. Gray. New York, Wiley and Putnam. 

 Boston, C. C. Little and Co. 1841. — Few authors, at least in the En- 

 glish language, have been equally successful with Dr. Lindley in render- 

 ing real science intelligible and attractive to the general reader. This 

 work, " written in the hope of providing the intelligent gardener, and the 

 scientific amateur, correctly, with the rationalia of the more important 

 operations of horticulture," has supplied a very important desideratum, 

 and is deemed indispensable to every gardener and amateur cultivator in 

 Great Britain. We presume it will be equally prized in this country, 

 where a taste for horticulture is so widely diffused, and where a work, 

 which conveys this kind of information, is so greatly needed. This edi- 

 tion is very neatly printed in the 12mo. form, and is afforded at an ex- 

 tremely moderate price. 



21. Corresponding Magnetic Observations, by Prof. A. D. Bache of 

 Philadelphia, and Prof Lloyd of Dublin. — It is with much pleasure 

 that we republish from the Proceedings of the Royal Irish Academy, (for 

 June 22, 1840,) the following account,! by Prof Lloyd, of Dublin, of a 

 series of simultaneous magnetic observations made in November, 1839, 

 by Prof Bache at Philadelphia, and Prof Lloyd at Dublin, with a view to 

 determine whether any deductions could be drawn from them for deter- 

 mining differences of longitude. The results are very satisfactory, inas- 

 much as they prove definitely that " no correspondence whatever exists 

 between the smaller changes of declination at Dublin and at Philadel- 

 phia, and that the determination of differences of longitude by means of 

 the magnet at such distances is impracticable." — Eds. 



* Which is over eighteen inches wide at the top, and from seven to eight at the 

 bottom, and lined with a metallic lube. 



t This account has been slightly abridged, to accommodate it to the crowded 

 state of our pages. — Eds. 



