Height and airspeed computer, Mark IA

British Metal Engraving Company Ltd

c. 1945

Circular slide rule, Height and Airspeed Computer Mark IA, metal, made by British Metal Engraving Company Ltd, United Kingdom, 1945

Powerhouse

A circular slide rule with multiple rotating discs and printed scales for calculating height and airspeed. It has a central black knob and metal pointers. The Mark IA Height and airspeed calculator consists of a metal circular disk base, with two concentric circular slides and two further attachment slides. The inner disk, which can be rotated 360 degrees, features a set of instructions in five steps on how to use the devise as well as two marked scales around the circumference, 6:50 in black and 60:500 in red. The slide also has a central message, "FOR USE ONLY WITH ISOTHERMALLY CALIBRATED ALTIMETERS". The second, slightly larger, slide is fixed in place and has two scales on the left and right. The left scale, ranging from -60:40 degrees is linked with the temperature slide attachme