Thorn Alpha 9
This lantern came from Bob Cookson, and was used somewhere in East Sussex, and entered my collection on Wednesday, 20th April 2005. Although the Alpha 9 was used within the City of Derby, it was more commonly in the South Derbyshire, North-west Leicestershire and North-west Derbyshire areas, but today is rather rare. Both the separate gear (which this one is) and integral gear versions are used.
The most distinctive feature of the Alpha 9 is its nugget-like bowl, which is also something of the lantern's biggest Achilles Heel - the clip used in securing the bowl is not quite sturdy enough to hold it, in the event of water gathering in the bowl, or the bowl being struck by tree branches in blustery weather.
The canopy tapers marginally towards the front of the lantern. The NEMA socket has probably been fitted for the lantern's entire life as the wires to and from it are connected to a secured terminal block. The majority of Derbyshire examples featured a two-part photocell.
The underside of the bowl is free of refractors or any other means of light diffusion for that matter.
A heat mark is visible on the inside of the canopy, revealing just how many thousands of hours' service this lantern has operated.
This photograph shows a close-up of the terminal blocks that connect the internal wiring with the outgoing cables, with the termination of the three cables for the NEMA socket just visible to the left.
Following a clean, the Alpha 9 was attached to a wall bracket on Friday, 18th May 2018.
With the lantern activated, the bowl refractors help to dissipate some of the horizontal light emitted downwards, although the limited refraction capabilities of the bowl will not reduce this by much.
Lamp switch-on video:
Testing with my energy monitoring device revealed the following results.
| Test Voltage (V) | Current being drawn at full power (A) | Measured wattage (W) | Apparent Power (VA) | Frequency (Hz) | Power Factor | True Power (W) | Difference to rated wattage | Percentage Difference |
| 240.4 | 0.57 | 110 | 137 | 49.9 | 0.8 | 109.62 | 19.62 | 22% |
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