Building Research Station photographs and notes

In two parts:

1) 28 photographs of a differential analyser which was made at the Building Research Station in the early 1950s. The photographs show the differential analyser during the course of construction

2) Bound photocopied lectures on calculating machines comprising: E137 Description of Hand Calculating Machines; E140 The Use of Hand Machines - Addition and Subtraction; E147 The Use of Hand Machines - Multiplication; E152 The Use of Hand Machines - Division; E153 Some Special Types of Calculations