Talk:Caledonian Railway 72 Class

Classification
I am struggling with the classification of these engines. The 72 Class is OK but the others are a muddle. According to BR Database BR 54461 to 54476 are all 113 Class. According to Rail UK they are 713 and 918 Classes. Can anyone explain? Biscuittin (talk) 15:53, 21 June 2012 (UTC)


 * The British Locomotive Catalogue 1825-1923 by David Baxter (vol.4 pp.100-101) has them all as the same class with identical dimensions but in two series. The first series (Nos. 113-124 BR 54461-66) were built at St Rollox works whereas the second series (Nos. 928-937 BR 54467-76) were built by the North British Locomotive Company. I have no idea where '918' comes from. --Das48 (talk) 16:33, 21 June 2012 (UTC)
 * Baxter shows (p.91) that the Caley 918 Class were 4-6-0, not 4-4-0. McIntosh, built 1906. -- Red rose64 (talk) 18:00, 21 June 2012 (UTC)
 * Thank you. Biscuittin (talk) 18:20, 21 June 2012 (UTC)

Pressure conversions
There seems to be something wrong with Wikipedia's pressure conversion system: 175 psi, 180 psi - higher in psi but lower in kPa. I make them 1,207 kPa and 1,241 kPa repectively, using the factor given at Pascal (unit). Biscuittin (talk) 18:32, 21 June 2012 (UTC)
 * It's to do with the number of significant figures. 175 has 3 sig fig, but 180 has two (the 0 doesn't count). On conversion, they're rounded to the same degree of precision, so 1,210 has 3 sig fig (the 0 doesn't count) and 1,200 has two (the 00 don't count). You can force the accuracy by adding a final positional parameter:   gives 175 psi, 180 psi whilst   gives 175 psi, 180 psi. I'd go with the latter because it maintains the consistency of three significant figures. -- Red rose64 (talk) 19:21, 21 June 2012 (UTC)
 * Thank you. Biscuittin (talk) 19:37, 21 June 2012 (UTC)