1815,1 Scientific InielUgence. 313 



where he took a degree in medicine ; and liaving steadily regarded 

 as the iinal end of his studies the exploring the interior of Africa, 

 he prepared himself by the study of natural history in all its 

 branches, Eastern languages, and astronomy, geography, &c. In 

 1802 he left Gotha, accompanied by a young man of the name of 

 Jacobsen, and went to Vienna, whence he proceeded with some 

 difficulty to Constantinople, where he arrived in December, 1802. 

 Thence he went to Smyrna, which he quitted in October, 1803, 

 having previously explored the adjacent country. He then resided 

 at Aleppo, and afterwards at Damascus ; afterwards he examined 

 the geological structure of the country towards Jerusalem, Lebanon, 

 and Latitibanon. In 1805 he travelled through Arabia into Egypt, 

 and finally arrived at Cairo. During residence at this last place (for 

 two years) he transmitted his very valuable observations in separate 

 dissertations to Germany, where many have been published, and 

 many remain in the possession of his relations. In 1809 he quitted 

 Cairo, returned into Arabia, and in Nov, 1810 he was at Mokka, 

 since which no correct account of him has reached this country. 

 A report has been received of his death, but in a very suspicious 

 form. It would ho gratifying to his friends to know his fate, as they 

 would then be enabled to give the whole of his valuable researches 

 to the world, a part of which only has hitherto appeared in the 

 journal of his liberal friend Baron Von Zach. 



IV. Gas Light. — Conveyance of Steam in Pipes. — Smallest Angle 

 at which Objects are perceptible. 



(To Dr. Thomson.) 

 DEAR SIR, 



I have been much gratified by the information which has come 

 cut respecting the saccharometer, in consequence of my inquiry in 

 your Annals. The " Philosophical Intelligence" is a most interest- 

 ing part of that work. 



Permit me to suggest to you that accidents, arising from philoso- 

 phical negligence, if I may use the expression, — such as the late 

 explouon of a brewer's store cask, asid a recent accident with a gas- 

 light apparatus at Birmingham, — deserve to be recorded in your 

 Annuls, for obvious reasons. A fiiend of mine was going to light 

 two large maiuifactories with coal gas, but since the late accident he 

 lias betn undetermined whether to proceed or not. Will it he pre- 

 suming too much to ask your opinion respecting the new mode .of 

 illumination with gas? The o|)Iiiion of so exi)erienccd a chemist 

 and ]ihil()snpher would have a most benelicial influence. And what 

 sort of coal is to be [)-efened for producing the gas in question ? I 

 presume the diameters of the conduit pipes have hitherto litcn taken 

 at ranriofii, and tliat the pressure on tlic reservoir of gas for sending 

 a stream through the pipes has not yet been accurately observed, or 

 at least not puhlished. 



I am aUo desirous to inquire how far steam has hccn known to be 

 conveyed, or how far it prohatdy can be conveyed, for h.aiing water; 

 and how large the conduciipg pipes should be to produce a required 



