Compound2632

As far as I'm aware, no physical adjustment is made to the clocks in the satellites. The frequency corrections are made in software, along with all the other corrections you mention. It's the comparison with the master clocks on the ground that enables this correction to be made.

Exciting! (Apologies for thread drift!) What does note A say? Equally exciting is that the Midland brake compo for Plymouth has come from Bradford hand-in-hand with a Great Western brake compo for Kingswear. What date is this?

There are really just two rules in physics: What goes up must come down. What goes in must come out. Experience shows they're of general applicability.

The corrections are applied in software - there's quite a bit of post-processing which results in a prediction of the correction to be applied in real time.

I have the later version of the Zafira (a 1.6 litre 10 reg); before that I had the earlier version (a 1.8 litre 03 reg), both grey. I recall the first time I came out of the supermarket: "now which one is mine?" Not having memorised either the registration or exactly where I'd parked, I had to go round discretely pressing the key fob until one responded...

I've found the Facebook post again and there have now been several replies saying what you're saying but also pointing to known cases in the 1960s when the banker wasn't coupled up. The photo of the model could be interpreted as being shortly after the guard had uncoupled - but long enough after for him to have gone back into the cabin!

No, rather the opposite. The problem in the Ozarks is that they're all in the same inertial frame and don't move around relative to one another nearly enough.

There was a photo recently on a Facebook group devoted to "Realistic Railway Modelling" of a 4 mm (IIRC) S&DJR layout with the banker - an LMS standard 3F 0-6-0T, Bagnall to you, Jinty to the hoi polloi - dropping off the rear of a freight (I think this was on the other side of the hill to you). I asked what prototype practice was, since my understanding is that the general rule was that the banker should be coupled to the train it was assisting - following accidents in which trains had left the banker behind and the banker had then caught up, violently; this would mean coming to a stand at the top of the bank, to uncouple, though in some instances slip couplings were used, which exposes everyone to the same risk of catching up. However, there were many exceptions to the rule, the Lickey Incline being one such. So I was wondering what the rules or exceptions were on the S&DJR in your period. Needless to say, I didn't get a reply to my question from the Facebook poster!

Galileo has been designed primarily as a commercial system, with enhanced features for those commercial organisations willing to pay fees. A second is a second is a second in the inertial frame of the clock. The clocks in the satellites, doing their 90-minute orbits around the Earth are moving relative to the clocks on the ground, so as seen from the ground, the frequency of their 'ticks' is blue or red shifted relative to that of the clocks on the ground - the clock going past in its satellite is like the pitch of the siren of the ambulance wizzing past you. This is all explained by Einstein's theory of Special Relativity and the appropriate corrections applied by the algorithm your receiver uses. Also, the clocks in the satellites experience a weaker gravitational pull than the clocks on the ground, being further from the centre of the Earth (the acceleration due to gravity is a bit less up there), which results in a slight shift in their tick rate. This is all explained by Einstein's theory of General Relativity and again, the appropriate corrections are applied. As I'm sure you all know, the second of the SI system is defined in terms of the 'ticks' of a caesium atom - specifically the frequency corresponding to the energy gap between its two ground state hyperfine energy levels, such that this frequency is defined to be 9,192,631,770 Hz (the hertz being the reciprocal of the second, 1 s = 1/9,192,631,770 oscillations of the radiation corresponding to this energy level difference.) In order to build a primary frequency standard or clock - one realising this definition, and against which other clocks can be compared - one has to tickle the caesium atoms with microwaves at the right frequency to make them giggle. This is best done with about a million or so atoms, so that the giggling is loud enough to be heard. Also, the best results are got by tossing them up and checking that they're still giggling when the come back down about a second later - the so-called caesium fountain. (For the technically-minded, this means your microwave source has to have superb short-term stability.) If you had a bunch of caesium atoms at room temperature, they'd be all over the shop by the time they came down again, so they have to be got really cold so that they stay huddling together - within a few millionths of a degree of absolute zero. (This is done by sapping their kinetic energy using laser light.) So, instead of a single caesium atom at rest, we have a great crowd of them pushing and shoving and crying 'whoopee' as they ride the fountain, all of which gives rise to niggling little shifts in that hyperfine energy level splitting. These effects have all been studied to death, with the result that after thirty years of development, the best caesium primary frequency standards realise the SI second with an accuracy of around one part in ten to the power sixteen, or about a millionth of a gnat's whisker compared to the diameter of the Earth. Anyway, the point of this digression is twofold. Firstly, the clocks in the GNSS satellites are not as accurate as this but need to be sufficiently stable to hold their tick rate between synchronisations to the timing ground stations. These, again, are not as accurate as the primary standards but are syncronised to them, via the international timescale UTC. (The complexities of which I won't bore you with here.) Secondly, the General Relativity effect has to be taken into account both within the caesium fountain itself (the frequency shift is about one part in ten to the power sixteen per metre change in height above the centre of the Earth and the fountain is about 0.3 m high) and when comparing the tick rates of these primary clocks. The UK's ones are at the National Physical Laboratory in Teddington, SW London, a few metres above sea level, while the USA's are at the National Institute of Standards and Technology's campus in Boulder, Colorado, over 1.6 km above sea level. If you are interested and in the area, I would thoroughly recommend booking a place at the National Physical Laboratory's Open Day on 20 May, when some of my former colleagues will be showing off the caesium fountain primary frequency standards. (Spoiler alert: it's all happening in a high vacuum system under several layers of magnetic shielding, so you can't actually see the atoms going up and down!)

I meant, rather specifically, the North Sea from Nottingham. Certainly the Norfolk coast via the M&GN but that was rather further and, I think, a bit more up-market? The Midland was very good at getting to the sea by proxy, but more for goods than seaside holidays - Liverpool by the CLC, Southampton via the M&SWJR, Hull by the H&BR, etc. Bournemouth by the S&DJR is an counter-instance but again, a high-class destination, likewise the Ulster coast. Leave the hoi polloi to the Great Northern and Great Central!

A tradition established by vigorous Great Northern marketing, no doubt. The Midland did not reach the sea.

I feel sure that left to his own devices, sitting on the loo, he would have achieved a hole in one.

With Midland engines working through via the Met Widened Lines - right up to closure of the depot, Kentish Town Jinties. The Midland had a substantial network of coal depots south of the Thames, the furthest-flung being at Maidstone. In the 19th century, the Midland had been hand-in-glove with the Chatham, in mutual alliance against Watkin's South Eastern and Sheffield companies.

Re-reading the catalogue caption to 66779, it does say 26, not 25 - my error. That strongly suggests that the engine in 82368 (which is a print from LGRP neg 22165), which is captioned as No. 25, is in fact No. 26.

Can you get it to do ninety?

Apologies that the following photos are catalogue thumbnails. Indicator shelters fitted to the sibling of my avatar, the first of the Midland's Smith-Johnson Compounds, No. 2631 (which in rebuilt for survives as No. 1000) at Durran Hill shed, Carlisle, sometime in Aug - Sep 1902, for tests over the Settle & Carlisle line: [Embedded link to catalogue thumbnail of Midland Railway Study Centre item 81620.] Those look to me to have been painted and lined out to match the engine. Rather similar shelters, perhaps even the same ones, were in use in 1912 for testing 990 Class No. 993: [Embedded link to catalogue thumbnail of Midland Railway Study Centre item 66683.] There's evidently some work gone into matching the styling of the shelters to the locomotives! Back in c. 1890, Derby was using something much more shed-like with bigger windows, but mounted on one side only - not taking diagrams off both cylinders? [Embedded link to catalogue thumbnail of Midland Railway Study Centre item 82368.] The engine is No. 25, built in 1887, the first of the Johnson singles, with slide valves rather than the later piston valves. Side view: [Embedded link to catalogue thumbnail of Midland Railway Study Centre item 66779.] According to the catalogue caption, also fitted with a speedometer - is the shiny object on the valence below the shelter pat of that? The tender has a rear-mounted tool box, no coal rails, and no MR initials on the tank side, all pointing to pre-1892 condition, so these photos could date to 1887 when the engine was new. S.W. Johnson's Presidential Address to the I. Mech. E. in 1898 includes a figure showing diagrams taken with No. 26 of the same class (perhaps a misprint?) working London - Nottingham expresses. In addition to the cylinder pressure diagrams, there are also diagrams for steam chest pressure, blast pipe pressure, and smokebox vacuum pressure, at 48 mph, 60 mph, and 70 mph. (The smokebox vacuum pressure chart clearly shows the four chuffs per cycle but one wonders to what extent it has been smoothed out by the instrument response mentioned above.) F.W. Webb at Crewe was taking similar measurements on his compounds in the 1880s. This all goes to show that the scientific measurement of locomotive behaviour was well-established in the latter part of the 19th century. I wonder when and where indicator diagrams were first taken?

The same correspondent has pointed out that I had slandered Joe Greaves' indexing skills. Turton Vol. 8 pp 112-3 is an article on Wm. McElroy & Co. but on p. 113 a photo included as a partial shot of a McElror wagon provides a goodish view of an Albert Usher wagon, albeit at an acute angle. it's at Aylesbury behind a Met K class 2-6-4T, so no earlier than 1925. The lettering layout is slightly different, with more "fine print", unfortunately undecipherable.

I hadn't looked closely enough! Turner says that wagons similar to the Hurst Nelson example built by Pickering (implying for Usher) around 1900 were green, so that is as good as one is going to get. No. 519 photographed at Lydney Junction could be green: presented with such a photo, black is simply the default assumption, green being altogether so very much rarer. Yes, that's the photo to which I referred. Manufacturers have in the past been misled by such Hurst Nelson photos into producing yellow wagons with red ironwork etc. but the fact that there are in the HMRS collection Hurst Nelson photos of wagons built for the Caledonian, North British, etc. is more than sufficient evidence that this painting style was purely for the camera. But this something that @Skinnylinny at al. know perfectly well. I've had an email from a correspondent who reads here but does not post:

I wouldn't worry about that. When these carriages were built in the 1880s, 3' 4" was a common standard for nominal buffer centre height above rail, rather than 3' 5" which was standard by the end of the century. In any case, it's only a nominal dimension, the exact value on any day depending on the state of the springs and the weight of the load. If you're modelling it in its old age it would probably be down on its old springs a bit anyway.

Where are you looking. Joe Greaves' Index has three references: Ian Pope's PO Wagons of the Forest of Dean, which I don't have, Turton's Vol. 8, which appears to be a rare error in the index, and Simon Turner's PO wagons of the South East, Vol. 2, which covers LBSCR territory. Rapido's model doesn't quite correspond to either photo reproduced by Turner. There's a 6-plank end door No. 519, photographed at Lydney Junction in 1909, which appears to be black, and a Hurst Nelson official of No. 811, a 7-plank end door, unfortunately undated but with single-side brakes, so before c. 1912 [HMRS photo APB615, look it up on the HMRS website]. This is in Hurst Nelson's fancy photographic livery so Rapido's plain black is a reasonable assumption based on the photo of No. 519 - the layout of the lettering is the same. The business seems to have thrived before the Great War and struggled on for a while after. Turner gives some instances of repairs of Usher's wagons, by Hurst Nelson, Pickering, or British Wagon Co., either at Battersea or New Wansdworth, these repairs being at the expense of the LBSCR - i.e. wagons were damaged by that company's rough shunting. One wagon was so badly damaged it had to be sent to Pickering's works (presumably the works at Wishaw in Lanarkshire) on a LBSCR machinery truck - now there's an idea for Scottish modellers! Turner also refers to Usher having premises (probably rented from the railway company) at Battersea, a LBSCR yard. So, altogether, the evidence points to the sphere of operation being LBSCR lines in the London area rather than SECR, but that's not to say that as a factor rather than a merchant, Usher might not have had contracts to supply merchants based at SECR stations. Equally, the Lydney Junction photo suggests Usher may have been getting coal from Forest of Dean collieries - raising the question of what rout to London. But in the absence of any other evidence, he could well have also been getting coal from collieries in the west and east Midlands, Yorkshire, etc., so this wagon can plausibly turn up in a coal train on any of the principal routes from the north into London, in the pre-grouping period.

Turton Vol. 16 p. 119. The caption states that the photo was taken after reburishment by Charles Roberts in 1932; that date is no doubt inferred from the numbers painted (not chalked) on the solebar but I have a sneaking doubt that this is in fact a date; the legend seems to me to read 117/2/32 or possibly 167/2/32; a photo of No. 53 refurbished by W.H. Davis shows a similar legend 6/27 8A - going by the explanation given by Pope and/or Turton for similar markings on Gloucester wagons, these could well be order numbers for hire of second-hand wagons. Nevertheless 32 and 27 most likely do represent the year. There is another photo presumably taken on the same occasion of wagons 65 - 68 all fresh in the same livery. It's an interesting wagon as it carries a GCR "reconstructed" diamond-shaped plate as faithfully reproduced by Rapido, with 1904 date (which is better going than I can read on the photo). This indicates that the wagon was originally built before 1888 as a dumb buffer wagon, almost certainly not originally purchased or hired by Wadsworths; it seems to me probable that they only had them following this refurbishment by Charles Roberts. So we might be looking at a period of 1932 - 1939.

Ah yes, looking at it now: don't know how I missed that in the Joe Greaves index. Of course there's no guarantee the unusual squarish style of lettering would have survived the first repaint. From Turner's caption and text, one learns that this wagon and its nine siblings were built by Charles Roberts to the order of the British Wagon Co., which was a wagon financing and leasing firm, and one infers that they were on hire by Moger from that firm. Indeed, on the solebar one can see from left to right, Charles Robets' builder's plate, British Wagon Co. owners plate, and British Wagon Co. "for repairs advise" plate. Looking closely at a publicity photo of the model, one can see all three plates but I think the British Wagon Co. plates are a bit on the small side. Fastidious modellers will want to add the prominent chunky wooden door stops that give the wagon that extra bit of character. According to Turner, the wagons of this batch were sent direct from Horbury Junction to New Sharleston Colliery; if Moger had a regular contract with that colliery, then these wagons could be seen anywhere on the Midland main line between Normanton and Brent, round to Battersea Wharf (by Midland trip) and on the LB&SC between Battersea Wharf and the various South London stations at which Moger had depots.

Handsome is as handsome does, they say, and I never heard that these engines couldn't 'do'! And I do like that 12-wheeler, while lamenting that it's not in its original Great Northern splendour. The M&GN wagon is a curiosity. In fact pretty well all M&GN wagons are.

If the company has an entry in Turton's volumes there will be a company history. The snag is that many PO wagons were on seven-year hire with repaint at mid-term of contract, so it's probable that even if the hire was renewed, the livery would have "developed" by the grouping period - there was, over time, a tendency to larger lettering. PO wagons remained well-maintained and routinely re-painted right up to the outbreak of WWII. Ordinary (unfitted) railway company opens and vans had been pooled since the Great War. The great majority of PO wagons were requisitioned at the outbreak of WWII - effectively pooled. Moger's No. 232, the subject of Rapido's model, was the first-numbered of batch of ten built by Charles Roberts in 1911 [Turton Vol. 5 p. 61]. I've not traced the photo Rapido have used but Hudson Vol. 2 plate 91 is of Moger's No. 576, a Charles Roberts official photo of one of a batch of 30 built in 1920, in the same livery style as the model. It's possible that the LB&SCRy branding lasted for a short while after the grouping but Turton has photos of a couple of 1923 specification wagons built in 1928 and 1935 with MOGER in letters four planks high, so I should think it likely that older wagons were carrying that style by then. I think one can be reasonably confident that wagons built c. 1911 were still in service in 1939, barring mishaps.