116 



Scientific Intelligence. 



Of the total number noted, twenty-seven have occurred from San Luia 

 Obispo south, and of the thirty-two remaining, nine have been felt in 

 San Francisco at the same time they were observed at San Luis Obispo, 

 while the remaining twenty-three were felt at San Francisco and north of 

 that point. 



Notwithstanding we have had, what may perhaps be considered a fre- 

 quent recurrence of these phenomena, still there are but a very few of the 

 total number that would have excited attention south of the twenty-fifth 

 parallel of north latitude, for there they would be regarded as minor 

 affairs entirely. 



From all the facts in our possession relating to the phenomena on our 

 coast, it appears that the greatest preponderance in action, and severity 

 of effects, is exerted for the most part, south of Point Conception, for, 

 from this place, east, south and north, to near the Colorado, the most 

 conclusive evidence exists of very recent volcanic action having been ex- 

 erted on rather an extensive scale, which is also still persistent in several 

 localities within the area named, though in a minor degree. 



It would be interesting to examine what changes of level, if any, have 

 taken place in this State within the last five years ; but, as more ex- 

 tended observations would greatly assist us in forming conclusions on this 

 subject, I will defer that portion until a future day. 



2. Geographical Discoveries in Africa. — Dr. Petermanri's Mittheilungen 

 aus Julius Perthes' 1 geographischer Anstalt (1856, I.) contains a memoir 

 from J. Erhardt, one of the Missionaries of the Church Missionary Society 

 of England, illustrating a Chart of Central and Eastern Africa, prepared 

 by him, and his colleague, J. Rebmann. This memoir is accompanied by 

 strictures upon that portion of it which relates to a great inland sea, by 

 W. Desborough Cooley of London, and an explanatory article by the 

 Editor, Dr. Petermann. 



The chart of Messrs. Erhardt and Rebmann presents many interesting 

 details in regard to the mountains, plains, and rivers, as well as the cara- 

 van routes, and villages, between the equator and 10° S Lat., and east of 

 Long. 33° E from Greenwich. The chart also gives the supposed outline 

 of a great lake, lying for the most part west of 30° Long. E, as indicated 

 in the adjoining cut. Erhardt and Rebmann base their statement partly 

 on the observations of missionaries, but mainly on a collation of the 

 accounts of aboriginal traders. 



The memoir states that in the region described there are no mountain 

 terraces as have been supposed, but groups of mountains and isolated 

 peaks which are for the most part very steep, rising from a horizontal 

 plain, often standing near one another but never forming a continuous 

 chain. Between 2° and 13° S Lat., inward from the coast, Africa appears 

 as a great plain, varying scarcely enough in its elevation to give a course 

 toward the Indian Ocean for the Ofi, Sabaki, Rufuma, and other rivers, 

 which take their rise in the solitary mountains that have just been referred 

 to. At length the plain slopes towards the west and is there bounded by 

 a great sea, which is called Niandsha at its southern end, Ukereive at the 

 northern, and Niasa and Bahari ya Uniamesi along the coast. 



Central Africa has long been visited by the natives who dwell near the 

 Indian Ocean. In the interior they buy their ivory and procure their 

 slaves. The principal routes are three ; — viz., 



