623 



vviih a special view to this survey, was entrusted with the conduct 

 of an expedition in conformity with that recommendation. 



The author gives a circumstantial narrative of the expedition, 

 together with minute details of the instruments employed, and the 

 methods of observation adopted ; and extensive tables of the ob- 

 servations themselves, both as regards intensity and inclination, at 

 the different stations where they vvere made, occupying altogether 

 about 120 folio pages of manuscript. 



It results from the calculations founded on the data furnished by 

 these observations, that the geographical position of the point of 

 maximum intensity, where its amount is 1*88, is 52° 19''3 north 

 latitude, and 268° 01' longitude. The angle which the major axis 

 of the ellipse makes with the parallel of geographical latitude ia 

 57° 49''5 ; and the values of the semi-axes of the ellipse of 1*875 

 are 290 and 110 geographical miles rer.pectively. 



May 28, 1846. 



The MARQUIS OF NORTHAMPTON, President, in the Chair. 



" An Account of the desquamation and change of colour in a 

 Negro of Upper Guinea, West Africa." By the Rev. Thomas S. 

 Savage, M.D-, Corr. Member of the Boston Natural History Society, 

 &c. Communicated by Richard Owen, Esq., F.R.S. 



The subject of this narrative, named Talitoo Duari, is a member 

 of the Grebo tribe, the aboriginal inhabitants of Cape Palmas and 

 its vicinity. His parents were members of the same tribe and 

 natives of the same region. The father was of a decidedly black 

 complexion, while the mother was what is termed yeUoiv, the two 

 extremes observable in the tribe, and between which there is found 

 every variety of shade. In March 1844, when about twenty-five 

 years of age, Tahtoo was attacked with a quotidian ague, having 

 previously been in perfect health. The febrile symptoms subsided 

 in the course of a week, but were followed by a general desqua- 

 mation of the cuticle, leaving the subjacent skin of a dingy yellow 

 hue. A month afterwards, the same process, preceded by a similar 

 febrile attack, recurred, and was followed by still greater whiteness 

 ofthe newly-formed skin, resulting in the complete conversion of a 

 negro to a white man, retaining the characteristic features and hair 

 of an Ethiopian. This change was accompanied with great sensi- 

 bility in the skin to the heat of the sun and of fire, exposure to 

 which readily excited irritation, and even inflammation ; but the 

 general health soon became completely re-established. In the 

 course of three months, subsequently to this change, numerous 

 spots of a chestnut-brown colour made their appearance, first on the 

 wrists, then on the back of the arms, head and neck, and succes- 

 sively on the other parts of the body, forming by their extension 

 dark patches of various sizes; which, being scattered over the 



