Still stuck on finding a picture of this one, so here is what I have and what I am missing.
NavWeaps, British mines page, on S Mark 4 and 4*: "Hertz horn mine for 21 in (53 cm) torpedo tubes. This was the first British Hertz mine. Submarines E34, E45, E46 and E51 were modified to carry them. Total weight of 540 lbs. (245 kg), charge of 210 lbs. (95 kg) amatol. Actual size was 78 x 20.85 in (228.6 x 53 cm) including sinker."
IWM
MUN 5883, sectioned example, 1917, disruptive camouflage, 530mm dia x 173mm high, stamped N O.S 2788 G WMS TYPE IV *SM N 1917 1896 and broad arrow. Media not available online, licensing team only.
Two things I cannot reconcile:
- NavWeaps gives 78in but converts it to 228.6cm. 78in is 198cm, and 228.6cm is 90in. Which figure is the real overall length with sinker?
- The IWM history note attaches the Mark IV to E24 and the first British minelay off Heligoland on 3 March 1916. E24 was lost on 21 March 1916, so she can hardly have carried a 1917 mine. Presumably she ran an earlier S type. Does anyone know which?
Paperwork that should hold the plates, none of it digitised:
- ADM 189/74, Vernon Annual Report Mining Appendix 1917-1918, old service reference C.B. 1535, open document
- ADM 189/37 and /38 (Annual Reports 1917, 1918), ADM 189/72 (General Index 1916-1946) for the plate number
- ADM 186, "ARMAMENT: Torpedo, Anti-Submarine and Mine (Code No. 2/4)", 1917 and 1918 volumes
For anyone tempted by the Admiralty Technical History: I went through all 51 parts and there is no volume on mine types. Only Part 45 (minelaying bases) and Part 51 (paravane) touch mining at all. Full set is Kew ADM 275/19.
So: has anyone got a photo of a Mark IV, or scans of the S-series plates from ADM 189/74? Would save me a trip to Kew.
