> E Z Peaces wrote:
>>> R.H. wrote:
>>
>>>>> "John Martin" (clip) I'd suggest that it might be for measuring the
>>>>> frequency of AC current. Adjust the length of the arm until the
>>>>> amplitude of vibration is the greatest (that's what the semi-circular
>>>>> scale is there to measure), and read the frequency off the linear
>>>>> scale. ^^^^^^^^^^^^^^^^
>>>>> "The black part at the bottom appears to be made of bakelite." From
>>>>> the OP. There does not appear to be any electrical contact at the tip
>>>>> of the black part, nor is any mentioned. So I doubt that it is
>>>>> electrical. Also, I have trouble thinking of any way that all those
>>>>> angular adjustments and scales could be related to frequency. It
>>>>> looks like the straight scale is in the range aroud 60, which does
>>>>> support your suggestion.
>>
>>>> You're correct in that it's not electrical, there is no contact on the
>>>> bottom, nor are there any coils inside. I've shown it to a couple of
>>>> electrical engineers and we all agreed that it's some type of vibration
>>>> indicator, as was mentioned by Andrew, but we could only guess at it's
>>>> exact use.
>>
>>>> There is no company name or patent date on it, just some numbers on the
>>>> back that yielded nothing in a search. It does fit into a light
>>>> socket, and note that the back plate is shaped like a light bulb, a
>>>> couple possible answers that I've heard:
>>
>>>> -Used by a bulb manufacturer to test the strength of filaments
>>>> -Used to test the amount of vibration that a bulb would have to endure
>>>> in a particular machine, such as a large projector
>>
>>>> These are just guesses but I think they're on the right track. >>
>>>> Rob
>>
>>> Frank C Perkins
>>> US Pat 1,687,507
>>> granted Oct 16, 1928
>>
>>> Back about 1904 there was a Frank C Perkins who was a free-lance
>>> magazine author writing articles about the advantages of electricity for
>>> mine vehicles, cranes, boat propulsion, lighthouses, factory machinery,
>>> and wireless telegraphy.
>>
>>> He intended it as a general-purpose vibration meter. He says he chose a
>>> light-bulb base because checking light sockets was one purpose that came >>> to mind.
>>
>>> If you tuned in a vibration, you had to use a chart to find the
>>> frequency. It was designed with two weights. With no weight it could
>>> be adjusted up to 65 Hz (about 4,000 rpm). With the heavier weight it
>>> could be adjusted down to 8 Hz (about 500 rpm).
>>
>>> That sounds like good coverage of vehicle engines in 1928, among other
>>> uses. You'd just have to secure a light socket to your engine. >>
>>> This page shows a vibrometer designed for large machinery such as a >>> steam engine:
>>>
formatting link
>
> - spammer
>
> I agree...have you seen the Billy Mays infomercials on the steam
> engine test equipment? So annoying!
Spammer -B-Gone!