Telegraph block instrument
Telegraph block instrument; GNR. Harper's non-pegging absolute 1-needle 3-position/3-indication.
Details
- Category:
- Signalling & Telecommunications
- Object Number:
- 1999-8297
- credit:
- British Rail, Clapham
Telegraph block instrument; GNR. Harper's non-pegging absolute 1-needle 3-position/3-indication.