![](https://coimages.sciencemuseumgroup.org.uk/423/790/large_thumbnail_1994_8772__0009_.jpg)
![](https://coimages.sciencemuseumgroup.org.uk/423/790/large_thumbnail_1994_8772__0009_.jpg)
![](https://coimages.sciencemuseumgroup.org.uk/423/797/large_thumbnail_1994_8775__0002_.jpg)
Block instrument (sending/receiving)
![](https://coimages.sciencemuseumgroup.org.uk/421/741/large_thumbnail_1876_1451__0012_.jpg)
Single-needle block instrument
1845
![](https://coimages.sciencemuseumgroup.org.uk/54/742/large_thumbnail_1912_0005__0002_.jpg)
Clark's block signalling telegraph instrument, 1854
1854
![](https://coimages.sciencemuseumgroup.org.uk/425/839/large_thumbnail_1994_8774__0001_.jpg)
Block instrument (sending)
![](https://coimages.sciencemuseumgroup.org.uk/425/872/large_thumbnail_1994_8776__0005_.jpg)
Block instrument (sending/receiving)
![](https://coimages.sciencemuseumgroup.org.uk/421/771/large_thumbnail_1951_215__0012_.jpg)
Block instrument (lock and block)
1897
![](https://coimages.sciencemuseumgroup.org.uk/423/550/large_thumbnail_1964_330_19__0009_.jpg)
Two-plunger block instrument pattern 288
![](https://coimages.sciencemuseumgroup.org.uk/421/735/large_thumbnail_1964_330_40__0005_.jpg)
Block instrument
![](https://coimages.sciencemuseumgroup.org.uk/423/551/large_thumbnail_1964_330_37__0007_.jpg)
Block instrument (permissive indicating)
![](https://coimages.sciencemuseumgroup.org.uk/425/874/large_thumbnail_1994_8778__0003_.jpg)
Block instrument (sending/receiving)
![](https://coimages.sciencemuseumgroup.org.uk/425/865/large_thumbnail_1994_7262__0009_.jpg)
Intermediate block instrument
![](https://coimages.sciencemuseumgroup.org.uk/517/660/large_thumbnail_1999_7104.jpg)
London & North Eastern Railway train describer
1923-1948
![](https://coimages.sciencemuseumgroup.org.uk/425/740/large_thumbnail_smg00225061.jpg)
Lancashire & Yorkshire Railway Signalling School Model Railway Layout
1912
![](https://coimages.sciencemuseumgroup.org.uk/733/60/large_thumbnail_smg00455747.jpg)
Telegraph Block Instrument, Markham North
![](https://coimages.sciencemuseumgroup.org.uk/733/67/large_thumbnail_smg00455754.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/730/267/large_thumbnail_smg00455757.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/733/65/large_thumbnail_smg00455752.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/733/63/large_thumbnail_smg00455750.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/534/151/large_thumbnail_smg00358037.jpg)
Train describer (receiving) Great Western Railway
![](https://coimages.sciencemuseumgroup.org.uk/534/194/large_thumbnail_smg00358067.jpg)
Telegraph Block Instrument; Tyers Patent; 2-position type
![](https://coimages.sciencemuseumgroup.org.uk/533/575/large_thumbnail_smg00357298.jpg)
Telegraph block instrument
![](https://coimages.sciencemuseumgroup.org.uk/534/59/large_thumbnail_smg00357970.jpg)
Telegraph block instrument
![](https://coimages.sciencemuseumgroup.org.uk/533/573/large_thumbnail_smg00357293.jpg)
Telegraph block instrument, London Brighton & South Coast Railway
![](https://coimages.sciencemuseumgroup.org.uk/533/444/large_thumbnail_smg00357158.jpg)
Telegraph block instrument
![](https://coimages.sciencemuseumgroup.org.uk/534/147/large_thumbnail_smg00358033.jpg)
Telegraph Block Instrument, Great Western Railway Spagnoletti receiving type
![](https://coimages.sciencemuseumgroup.org.uk/535/43/large_thumbnail_smg00358199.jpg)
Block instrument, Great Central Railway (sending)
![](https://coimages.sciencemuseumgroup.org.uk/533/840/large_thumbnail_smg00357636.jpg)
Telegraph Block Instrument, Signal Relay, Great Western Rail
![](https://coimages.sciencemuseumgroup.org.uk/534/137/large_thumbnail_smg00358030.jpg)
Telegraph Block Instrument, Great Western Railway
![](https://coimages.sciencemuseumgroup.org.uk/534/123/large_thumbnail_smg00358026.jpg)
Telegraph Block Instrument, Spagnoletti type
![](https://coimages.sciencemuseumgroup.org.uk/535/16/large_thumbnail_smg00358143.jpg)
Telegraph block instrument, old form of bell instrument
![](https://coimages.sciencemuseumgroup.org.uk/534/150/large_thumbnail_smg00358036.jpg)
Train describer (receiving)
![](https://coimages.sciencemuseumgroup.org.uk/535/65/large_thumbnail_smg00358221.jpg)
Single-needle telegraph block instrument
![](https://coimages.sciencemuseumgroup.org.uk/533/445/large_thumbnail_smg00357159.jpg)
Three-wire block instrument
![](https://coimages.sciencemuseumgroup.org.uk/534/352/large_thumbnail_smg00358436.jpg)
Tyer's One-Wire Three Indication Block Instrument
![](https://coimages.sciencemuseumgroup.org.uk/535/44/large_thumbnail_smg00358200.jpg)
Block instrument with spagnoletti flag indicator (incomplete); GWR. Tyer's style
![](https://coimages.sciencemuseumgroup.org.uk/423/541/large_thumbnail_1995_7087__0013_.jpg)
Lock & Block Type Telegraph Block Instrument
![](https://coimages.sciencemuseumgroup.org.uk/517/664/large_thumbnail_1999_7103.jpg)
Train describer, London & North Eastern Railway
1923-1948
![](https://coimages.sciencemuseumgroup.org.uk/733/61/large_thumbnail_smg00455748.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/733/62/large_thumbnail_smg00455749.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/733/66/large_thumbnail_smg00455753.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/730/266/large_thumbnail_smg00455756.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/733/59/large_thumbnail_smg00455746.jpg)
Lock and Block Type Block Instrument
![](https://coimages.sciencemuseumgroup.org.uk/733/68/large_thumbnail_smg00455755.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/733/64/large_thumbnail_smg00455751.jpg)
Telegraph Block Instrument, Lock & Block Type, W R Sykes & Co
![](https://coimages.sciencemuseumgroup.org.uk/535/30/large_thumbnail_smg00358162.jpg)
Siemens Bros. block
![](https://coimages.sciencemuseumgroup.org.uk/534/141/large_thumbnail_smg00358031.jpg)
Telegraph Block Instrument, Great Western Railway
![](https://coimages.sciencemuseumgroup.org.uk/534/211/large_thumbnail_smg00358078.jpg)
Block instrument (sending/receiving)
![](https://coimages.sciencemuseumgroup.org.uk/535/45/large_thumbnail_smg00358201.jpg)
Block instrument (sending)
![](https://coimages.sciencemuseumgroup.org.uk/534/149/large_thumbnail_smg00358035.jpg)