I was interested to see John Arrowsmith's article about Gauge '2' but I don't think his description of Gauge '2' originally being 64mm gauge or a scale ratio of 1:22.5 is correct.

The 'gauges' introduced by Marklin in 1891 were Gauge I (48mm), Gauge II (54mm) and Gauge III (75mm). It should be noted however that these measurements were made from the centre of each rail (and not the inside rail edges). If we assume a common rail width of 3mm, then (by todays standards) we would call them 45mm, 51mm and 72mm respectively. So Markilin Gauge 'II' was 51mm which converts almost exactly to 2" (2.008" ). Nor was the scale 1:22.5 – it was 1:28.25 (as a comparison, Gauge '3' is correctly scaled at 1:22.6  – with LGB 'G' being 1:22.5 (Metre-gauge on 45mm track)

Please also note that Marklin Gauge 'III' is not the same as the (UK) Gauge '3'

I think the confusion with respect to Gauge '2' being 64mm probably arises from the fact that the German IG Spur II group use 64mm track for it's standard gauge stock (and 45mm (Spur IIm) & 32mm (Spur IIe) track for it's narrow gauge stock – all scaled at 1:22.5) See IG Spur II for further detail…

The early days of "Toy" railways was very confusing in terms of the gauge 'standards' , with many vendors using either different names for the same gauge or different gauges with the same name. There is a brief history of this confusion on the G3S website. See A Little Toy History

However, In the UK the five standard model gauges were recommended by a subcommittee of the Society of Model Engineers on 1st February 1899 and (of course) these gauges were stated in Imperial measure. Now you can convert these gauges into metric (as is now common in G1 and the smaller scales) but they were originally all defined in Inches. So G3 is not 64mm, it's 2.5" or if you must use millimetres then 63.5mm – not because the 0.5mm is crucial but because it confuses two different based standards – Metric & Imperial.

Anyway, not to detract from an interesting article – just to trying to correct a small detail before it becomes part of the accepted 'lore'.

Regards,

IanT

Edited By IanT on 23/05/2023 00:22:44

Yes David, manufacturers were very 'loose' in terms of "scale" and approximations were used.

In the history of Gauge '3' – early 2.5" gauge stock was built to 1/2" scale (with 3.5" gauge being 3/4" and 5" being 1" "scale). This persisted until sometime between the great wars, when the scale in general use for G3 changed to 17/32" . Not everyone followed suite and some very well known 2.5" builders continued with 1/2" scale (CM Keiller for example). Gauge '2' never really went through this evolution as (stated in the article) it fell out of fashion fairly quickly with the larger retailers tending to simplify the choice of gauges offered.

With regards "True Scale" that is very simply stated as being the track ratio between prototype & model. In UK 'standard' gauge terms that involves dividing 56.5" (4ft 8.5" ) by the model track gauge in inches. You can then use that scale ratio to come up with the "scale" normally referred to (or to find out how far adrift it is). So G2 (track ratio 1:28.25) is 0.425" (10.8mm) per foot "true scale" (with 7/16" being 0.4375" (11.11mm) per foot). It's interesting to note that G2 at 7/16th was over-scale, whereas G3 at 1/2" was underscale. One of the drivers to moving to 17/32" in G3 was the desire for larger mechanical clearances but this pressure would not have been present in G2.

So there we have it. All the larger 'scenic' gauges quickly declined after WW2, with the smaller "Table-Top" model railway scales becoming not only far more affordable but also practical for indoor layouts. In terms of scenic garden railways, 16mm (N/G on 45/32mm track) was the first to 're-emerge' followed by G1 and then (some 20 years later) by G3. We are all constrained of course by the availability of track to run on but also by the availability of new product. It's taken over 30 years to build G3 back to the point where it is no longer just a 'scratch builders' scale with a good range of commercial support. With the advent of laser and 3D print technology some of these barriers are being reduced but I think G2 is unlikely to be anything but a Collectors gauge looking forward – but of course a few dedicated enthusiasts can make a huge difference (as was the case with G3).

I wish them every success.

Regards,

IanT

Edited By IanT on 23/05/2023 11:23:23