Metric Imperial holograph rule

I found a 12" plastic holograph rule in my late father's wooden tool chest.

Is it still possible to buy these and if so , where from ?

Seems like a good idea to me. You just tilt the rule to get either metric of imperial figures.

What age would this be from, 70's ?

Mike.

Edited By sparky mike on 23/06/2021 08:50:06

I must admit that is the first time I have heard of these, but unless it was heavily patented, one possible maker is Blundell--Harling, of Weymouth.

This is an independent firm that used to make slide-rules but with the loss of that market, it turned successfully to what it does now, manufacturing drawing-boards and many types of measuring-rules and scales.

I have a 6" version of this rule. I obtained it in a 'swap' with someone at school in the early '70s. Possibly this was given out as a gift at a trade exhibition or similar. I don't know the significance of the name on the reverse.

The name is " significant " as almost certainly the manufacturer, but whether the firm still exists is another matter.

I just found a name on the rear, so small I had missed it.

It is made by Varivue. MFG USA. Pat.NO. 2.815.310 .... also Pat no.2.399.938 (the 3 might be 2 or another number. A job to read.)

Mike.

I've never seen one, are you sure it is a holograph and not a diffraction grating?

It seems to work like the images on some credit cards. There is another name for it but can't remember it.

One for sale on UK Ebay right now but none on the US Ebay, which is the place where I thought they would be found. With the US Pat. number it should be possible to look that up and it will describe the technique in detail I would think.

Mike.

I used to have one, went the way of most advertising items. Can’t remember where I got mine.

Not a hologram but a set of grating like lenses with two printed images below. Changing the viewing angle causes one image or the other to appear. The lenses were normally just embossed plastic sheet.
More commonly found in childrens novelty items were the illusion of movement is produced.

Not very much use for preceion meaurement, at least one scle wll have parallax error by design.

Robert G8RPI.

Edited By Robert Atkinson 2 on 23/06/2021 22:27:04