390 Scientific Intelligence. [Nov. 



parts. I shall give for the satisfaction of my readers the titles 

 of the different parts. 



Part I. Of Halley's Lines of Declination, and of their Altera- 

 tion from the Year 1600 to 1800. 



Part II. Of the Lines of Inclination and their Magnetical 

 Force. 



Part III. Preliminary Estimate of the Number of Magnetic 

 Poles of the Earth; their Position, and their Periodical Revolu- 

 tion round the Pole of the Earth. 



Part IV. Calculation of Halley's Lines, according to the first 

 imperfect Theory of Euler. 



Part V. Mathematical Theory of Magnetism, with Experi- 

 ments. 



Part VI. Use of this Theory in the Theory of Magnetic Decli- 

 nation, Inclination, and Strengths. 



Part VII. A more accurate Determination of the Position of 

 the Magnetic Poles, of their Size, and of the Differences 

 between their absolute Strength. 



Part VIII. On the Diurnal Variation of the Needle. 



Part IX. On the Magnetical Phenomena, accompanied with 

 Light or the Aurora Borealis. 



This book I presume will be written in the German language ; 

 at least I have seen it announced in the German periodical 

 works. 



VI. Sand of the River Rhine. 



From the observations and experiments of Mr. Koelreuter, of 

 Karlsruhe, we learn that the sand of the Rhine consists of the 

 following substances : 



1 . Sandy red iron stone. 



2. Chromiron. 



3. Quartz sand. 



4. Mica sand (very small in quantity). 



5. Common fine fohated gold. 



The chromiron, according to the analysis of Koelreuter, was 

 composed of 



Protoxide of iron 98 



Oxide of chromium 2 



100 



The foliated gold, being subjected to a chemical analysis, was 

 found composed of the following constituents : 



Gold 93-5 



Silver 6-0 



99-5 



The sandy red iron stone being analyzed, yielded the following 



constituents : 



