404 REPORT—1905. 
Southern Cape Colony Northern Cape Colony Transvaal 
q Griquatown Series 8 eokee Series 
Slates E g | Campbell Rand £ & | Dolomite Series 
SAE Dolomitic Lime- = 8 Series Bn 
Beds ar oR 
stone om an ; 
Grits ie ® \Keis Series = Black Reef Series 
my 
SNR INI INSISTS PRIN IN ININ EARRING 
Cango Conglomerate Amygdaloids of the Ventersdorp Sys- 
and Ibiquas Series Vaal River tem 
(in part) 
PDL OY PRAAFNRRLRLILIIO RII ~weweyyyeyeye ee ™w 
(nissing) (missing) Witwatersrand 
System 
Malmesbury Seriesand Namaqualand Series Swaziland Series 
Granite and Granite and Granite 
N.B.—The wavy line -~~~~~~~ indicates the presence of an unconformity. 
5. An Instrument for Surveying Deep Boreholes. By Dr. F. H. Harcu. 
The author described Mr. Oehmen’s instrument for surveying deep boreholes, 
and Mr. Payne Gallwey gave an illustration of the use of the instrument. By this 
ingenious instrument the deviation from the vertical and the direction of the 
deviation are recorded by taking photographs of the position of a plumb-bob and 
a magnetic needle at any desired point in the borehole. The photographs are 
taken by means of two small incandescent lamps, which are illuminated by a dry 
battery after the instrument has been lowered to the desired point by means of a 
time-contact regulated by a watch. The amount of deviation and its direction are 
calculated from the photograph after the sensitised paper has been developed at 
the surface, and check results are found to be most consistent. The amount of 
deviation is calculated by measuring the distance between the centre of the photo- 
graph of the plumb-bob and the centre of the disc, the length of the plumb-bob 
being a known factor. ‘The direction of deviation is obtained from the photograph 
of the magnetic needle, the correct orientation being fixed by two pin-pricks, which 
have the same relative position both on the photograph of the needle and on that of 
the plumb-bob. 
6. On the Geology of Basutoland. By Rey. 8. 8S. Dornan. 
The rocks of Basutoland belong to the Stormberg series of the Karroo system 
and consist of— 
nee 
. Volcanic beds ‘ . 600 to 4,000 feet. 
3. Cave sandstone. > 4 - 150 to 3800 feet. 
2. Red beds . . * : . 800 to 500 feet. 
1. Molteno beds + +  « « 600+, (exposed base not seen). 
together with surface-and recent accumulations. 
The Molteno beds comprise sandstones, shales, and mudstones, grey and greenish 
in colour, locse in texture, and presenting a glittering appearance upon fresh frac- 
ture. Nodules also are of frequent occurrence. 
Plants have been found in the Matabele district of Griqualand East, and a 
few, so far, in Basutoland. The Molteno beds contain thin seams of coal. Several 
are known to exist in Basutoland, but are not worked (except in one instance) by 
the natives, who are afraid of the white man, as they say that if they allowed the 
whites to prospect for minerals they would lose their country. Conglomerates 
