Before computers, we relied on t-squares, rulers & ink. Workers map Cambridge electrical system in 1950.
 
																																												Before computers, we relied on t-squares, rulers & ink. Workers map Cambridge electrical system in 1950.
 
																									 
																									 
																									 
																									 
																									 
																									 
																									 
																									 
																									 
																									 
																									 
																									 
																									
Ah! Good old days of different shapes of rulers 🙂