Cambridge Philosophical Society. 65 



termining the height from observations at one place by the help of 

 an hypothesis, gave the height 53*9 miles, which is a near approxi- 

 mation to the height found by the trigonometrical method for 

 8 h 25 m . 



The author concludes that the meteor occurs immediately beyond 

 the ordinary limits assigned to the earth's atmosphere, and from that 

 to very much greater altitudes, as shown by many other calcula- 

 tions ; and states his conviction that the meteor will be some time 

 observed with much more accurate means than hitherto, from its 

 connexion with the earth's magnetism. 



February 23, 1846. — Analytical Investigation of the Disease pre- 

 valent in the Potato during the year 1845. By Geo. Kemp., M.D., 

 Pet. Coll. 



This communication may be resolved into two parts ; the analysis 

 of the diseased portion of the potato, as compared with Boussin- 

 gault's analysis of the healthy tuber, and certain deductions derived 

 from the empirical formula? proposed as representing their respective 

 compositions. 



The author recognises three stages of the disease : the first ap- 

 pearing as dark brown patches under the skin ; the second as striae 

 of the same colour proceeding towards the centre ; and the third as 

 a soft, pultaceous, blackish, and offensive mass, in which all traces 

 of organization are lost. 



From the impossibility of isolating the portions affected by the 

 disease, in the first two stages, from the surrounding sound parts, 

 the examination was principally directed to the third stage. 



A potato having been selected in which the above characters 

 were well-developed, a sufficiently large portion for comparison still 

 remaining perfectly sound, gave the following results as indicative 

 of the relative proportions- of organic and inorganic matter in the 

 sound and unsound part. 



Of the sound portion, — 



I. 247 milligrammes gave 10*5 milligrammes of ash. 

 II. 205-5 85 



Of the unsound portion, — 



I. 311 milligrammes gave 18 milligrammes of ash. 



II. 234 13 



III. 236 135 ... 



Or, reducing to 100 parts, the sound portion consists of — 



I. II. 



Organic matter 95-75 95-86 



Inorganic matter . . 4*25 4-14 



lob^bo 100-00 



whilst the unsound portion gives, — 



I. II. 



Organic matter .... 94*22 - 94-45 

 Inorganic matter. ... 5-78 5-55 



100-00 10000 



Phil. Mag. S. 3. Vol. 29. No. 191. July 1846. 



