Gauge 1 is a toy train and model railroading standard, popular in the early 20th century, particularly with European manufacturers. Its track measures 1.75 inches (44.45 mm), making it larger than O gauge but slightly smaller than wide gauge, which came to be the dominant U.S. standard during the 1920s.
No 1 gauge was standardised, according to Model Railways and Locomotive magazine of August 1909 at 1 3/4" or 44.75 mm. The distance between the wheel tyres at 1 17/32" or 39 mm and between the centre of the track 48mm (no inch equivalent suggesting it was metric users requirement only). The wheel width was set at 19/64" or 7.5 mm.
Interestingly gauge, rather than scale, seems to be used more in the early days. For the record the four gauges for which standards were adopted were No. 0 (commonly called O gauge nowadays), No. 1, No. 2 and No. 3.
1 gauge survives today as it is used by the modern G scale, a popular standard for outdoor model railroads.
Initially popular in the United States now in the UK, 1 gauge lost popularity due to World War I, which dramatically decreased foreign imports, allowing the U.S. wide gauge standard to gain traction. After the war, most surviving U.S. manufacturers switched to wide gauge. Today, though, there are now lots of gauge 1 layouts in UK.
Although vintage 1 gauge trains use the same track standard as modern G scale, scale modeling was not a primary design consideration in 1 gauge's heyday, so the actual size and scale of the locomotives and cars varied. Generally, 1 gauge equipment worked out to approximately 1:32 scale. G scale at 1:22.5 means the 1 gauge track represents 1,000 mm narrow gauge track. Such railways are to be found in, among other places, in Switzerland, the inspiration source for many commercial G gauge models.
By comparison, 1 gauge's 1:32 scale makes it nearly three times the dimensions of modern HO scale, the most popular size of today.
Due to the size of the locomotives it is possible for them to be powered with live steam, which to many is a large advantage as they are cheaper than traditional live steam garden railroads. These are usually fired by gas or methylated spirit, which are both very popular. Another form, which is becoming popular is coal, which gives the user the unforgettable smell that only steam locomotives carry.
Aster Hobbies Ltd. in Britain produce gauge 1 items, mostly coal and meths fired.
Märklin, in Germany, also produces two different lines of 1 gauge equipment, one cheaper, made of tin plate metal, and less detailed than their premier line, which is super-detailed and expensive.