Thanks Pieter, the dankie was easy to find, I don't know why I couldn't get the translation for seeppot.
Whole paragraphs about the seeppot mortar contained here are also in the two documents DD first posted, but there is also some additional information on the mortar.
The specifications of the 8-inch Boer mortar were:
Calibre 8-in (203 mm)
Weight of gun 9 cwt (460 kg)
Ammunition Common & star
Range 2000 yards (1830 m) approx.
History
During the early 1880s the Transvaal Republic conducted a number of small internal campaigns against native tribes, many of these ending up in mountain sieges. To assist, a howitzer and a mortar were bought from the Cape Colony. The howitzer (see last month's article), and hence presumably the mortar, arrived in Pretoria from King Williams Town on 7 April 1882.
In Boer hands the mortar was dubbed "Seeppot" (Soap pot), because of its resemblance to the big three legged pots used to cook soap and the large volumes of smoke it produced when fired!
One incident with this mortar was recorded during the 1882-1883 campaign against the tribal chieftains Mampuru and Nyabęla (Njabel). During the siege of an enemy position, Commandant HPN Pretorius, later CO of the Staatsartillerie (State Artillery), used the mortar to bombard the strongpoint with shells filled with lead (probably to pound down stone walls). After he observed the enemy recovering some of these shells and placing them in a fire to melt the lead out in order to cast bullets, he had the next shell filled with black powder. Instead of fitting a time fuze to it, the opening was carefully covered with lead before being fired into the enemy's positions. The consequences of this shell being placed into the fire can only be imagined and seven tribesmen are said to have died of the blast with several more wounded.
During the Anglo-Boer War of 1899-1902 this antique piece again saw service, this time outside Ladysmith during the siege of the town. Although obsolete by then, it was presumably used to fire star shells at night to provide light. The only known photo of Seeppot was taken on Vaalkop outside Ladysmith during the siege.
Burghers posing with “Seeppot” on Vaalkop during the siege of Ladysmith Nov 1899-Feb 1900. Note the burgher behind the rammer/sponge is standing with two bagged charges of black powder in his hands while smoking a pipe! Again, do not try this at home…
Close inspection of this photo revealed that the Boer mortar originated from the British gun founder, Bailey Pegg & Company (BP & Co). Documents on captured Boer Artillery in the British Public Records Office (WO32/7028) and a Transvaal Staatsartillerie letter in the Pretoria Archives identified this specific mortar's serial number as No.16. The photo shows the Boer mortar mounted on a wooden mortar bed with a trial and wheels axles. To transport it the bed had wooden spoke wheels that had to be removed before it could be fired. To ignite the charge it seems that a friction tube and lanyard was used.
When the siege of Ladysmith was lifted at the end of February 1900, Seeppot was rolled down Vaalkop and left there for the advancing English. Fortunately, while falling back from the Tugela front, Major Lood Pretorius of the Staatsartillerie and a couple of his men found the poor old mortar abandoned at the foot of the hill and saved it. It was presumably transported back to Pretoria by rail, because on 5 June 1900 it was found abandoned in Pretoria by the British. After the war it was shipped to England aboard the Avondale Castle, leaving South Africa on 30 December 1903. In 1904 the mortar was given to the City of Manchester as a war trophy. Unfortunately it is doubted whether it survived the scrap drives of World War II...
Epilogue
Fortunately two similar 8-in BP & Co. mortars survived in South Africa. Both are Mark IV pieces mounted on iron mortar beds manufactured for the Board of Ordnance. Of these, No.24 today guards the entrance of Fort Klapperkop in Pretoria and is inscribed with the date 1855 and a weight of 9-1-4 (9x112 + 1x28 + 4 = 1040 lb.) The second, No.4, is kept at the SA National Museum of Military History in Johannesburg and is dated 1849 with a weight of 9-0-18 (1026 lb.) The date of manufacture of the Boer mortar therefore must have been somewhere between 1849 and 1855. This disposes of earlier historians' suggestions that Seeppot was also in action at Blood River in 1838!
The mortar on display at the SA National Museum of Military History was used by the Cape Mounted Rifles at Mount Morosi in Basutoland during the 1878–1879 Gun War. It was later taken to Umtata where it served as a time gun, being fired daily at 9am. It was donated to the Military Museum in 1951. It is quite possible that the Boer mortar also saw service on British side during the Gun War before being sold to the Transvaal.
Sources:
Breytenbach, JH: Die Geskiedenis van die Tweede Vryheidsoorlog, Vol. 1, Die Staatsdrukker, Pretoria, 1969
De Vries, G & Hall, J: The Muzzle Loading Cannon of South Africa, Private, Cape Town, 2001
De Vries, G: Cannon Research Projects Newsletter, No. 11, Jul 2004
Ferreira, OJO: Geschiedenis, Werken en Streven van S.P.E. Trichard, RGN, Pretoria, 1975
Government-Secretary & Commandant General: Incoming Letters, Transvaal Archives, 1895 to 1899
Hall, DD: The Hall Handbook of the Anglo-Boer War, University of Natal Press, Pietermaritzburg, 1999
Haupt, DJ: Die Staatsartillerie van die Suid-Afrikaanse Republiek, MA-UP, Pretoria, 1946
Preller, GS: Historiese Opstelle, Van Schaik, Pretoria, 1925
Pretorius, JL: Ons Suidafrikaanse Militaire Tradisie, Die Brandwag, 28 June 1910
Pretorius, JL: Unpublished memoirs, Private collection, Pretoria
War Office Documentation 1899-1904, Public Records Office, Kew London and National Archives, Pretoria