From a document titled, “INITIAL EQUIPMENT MANUAL FOR SERVICE SQUADRONS IN THE AIR SERVICE, AMERICAN EXPEDITIONARY FORCES”

APPROVED BY G. H. Q.

SEPTEMBER 12, 1918

INSTRUCTIONS FOR “DREYER” OXYGEN APPARATUS

1. Apparatus (Dreyer).

The apparatus or regulator as used by the British and United States Air Services consists of an automatic aneroid controlled instrument so designed as to furnish the deficiency of oxygen in the air at any altitude.
Oxygen from the storage cylinder enters the regulator at approximately 2200 pounds depending upon the pressure in the storage cylinders. This initial pressure is reduced to atmospheric pressure and cannot exceed seventeen pounds to the square inch.
The hand controlled disc has the following markings : (a) Off., (b) One man (c) Two men. The disc must be set at the proper mark before starting a flight.
As the Airplane ascends the aneroids expand, thereby opening the port in the cylinder and the oxygen at atmospheric pressure is fed through to the low pressure outlet, to the pilot and observer, in increasing proportion the elevation increases.
The pressure gauge indicates the pressure remaining in the cylinder reservoir.
The flow indicator shows the flow to the passengers but does not revolve until the airplane is at an elevation of from 8000 to 10000 feet.
The apparatus itself should be screwed to the dash or side of the cockpit. There has been no definite place decided upon, as the type of plane and position of other instruments govern the location.
This apparatus is not to be dissembled or repaired in any way at squadrons and if not functioning properly a new apparatus must be installed.
Barring accidents and dirt the life of the apparatus is continuous. It should be installed in the pilot’s cockpit if possible but the services of the airplane and the location of other instruments will govern.

The rest of the document goes on to described the cylinders, masks in service etc.

So they were using LOX.

To answer your first question the RE8 is a candidate according to this web site.

http://www.simonahouse.com/index.php?route=product/product&product_id=129

Now the bit that interests me about this instrument. The supplier code is shown as S on both of these instruments. I have S as being the supplier code for Smith and Sons.
I will need more evident for, if the code was also used by Smiths.

Anyway powerandpassion you have given me another supplier code to add to my database on then (read, a short list that I would like to lengthen).

I found a picture of a 5C/4205 on my computer and it looks a bit different to the adapter shown above. The new boost gauge is central within the plate. I found this auction on Ebay which may give more details.

http://www.ebay.com.au/itm/RAF-AIRCRAFT-UNDERCARRIAGE-INDICATOR-ADAPTOR-PLATE-5C-4205-/171348617706?pt=UK_CPV_Aviation_SM&hash=item27e52c69ea

Smiths standard, NUMERALS AND LETTERS FOR AIRCRAFT INSTRUMENT DIAL AND PANEL MARKINGS

From this 1958 standard, the following is given:

8 ENGRAVED CHARACTERS
Where characters are produced by engraving the following shall apply:-

8.1 Square ended cutters shall be used for lines .030″ or greater in width.
8.2 For lines under .030″ wide the cutter angle must not be greater than 60° included.
8.3 Engravings which are to be filled with a colour contrasting with the background shall not be less than .010″ deep.
8.4 Engravings which are to remain the same colour as the background shall be not more than .010″ deep.
8.5 The preferred masters used for engraving the characters are:-

LETTERS Smith Civil and M.O.S. Taylor Hobson 2C.

NUMERALS Smiths Civil 1 to 3, 8 , 0 Taylor Hobson 2C.
Smiths Civil 4 to 7, 9 Special.

NUMERALS M.O.S. 1 to 5, 7, 8, 0 Taylor Hobson 2C.
M.O.S. 6 and 7 Special.

I hope this adds to the collective knowledge as I do not know if the reference to Taylor Hobson is in fact a font?

I have seen quite a few RFC airfield building plans in various locations on the net. Would this be of interest?

Ed
Will send you a couple of scans from a book I recently found. I have been meaning to write you an email on the subject, I guess it will be today.
It’s a book from the 1930’s which describes what specification steels etc are most suited for what applications.

I found the NACA No. 240 report on line.

https://archive.org/download/nasa_techdoc_19930081042/19930081042.pdf