Jet clock, modified 21B/116 clock

Thanks DaveF68, now my library is somewhat more extensive and to hand as required.
The picture is now making more sense of the following notes I made from what ever I was reading it from. I had noted the following:

“has a G S Clock (21B/116) modified with brass contacts for every minute that lights a light. Photo’s and wiring diagram are included.”

Does anyone have any information on what a 21B/116 clock looks like , who made it etc and what its orginal intended use may have been?

Barothermograph

I’m afraid no titles that directly suggest that barothermographs would be in them. They are not present in my 1927 copy of the AP1275 “General Instrument equipment for Aircraft”. In a 1930 addition, Airspeed recorders and Altitude recorders were added.
One of the FS publications is a “scales” book, which may have the item, good luck with finding a copy.

Def Stan fonts

I have found a reference in one of the UK defence standards on the fonts to be used in UK defence standards

Defence Standard 00-00 Part 2, Issue 2 Publication Date 30 July 1999 has the following section:

Part No: 2: Presentation and Management of Defence Standards

41.6 Font:
a. the default font shall be Times New Roman;
b. the default size shall be 12pt;
c. the default style shall be regular;
d. the default colour shall be black;
e. the security classification markings and draft headings shall be 18pt bold;
f. the front cover markings shall be 24pt bold;
g. in tables, illustrations and indexes the font size may be reduced to 10pt if it
enhances presentation and makes the best use of available space;
h. font sizes below 10pt shall not be used without the prior agreement of DStan.

While this covers current publications and gives an insight as what they may have been in the past, any other references to UK military publication presentation standards over the years would be appreciated.