Brass lens - where does the spacer go?

[ajmiller]

A few years back we found this lens in my French wife's family house when clearing it out to sell. It came from a magic lantern as I recall but can't be sure. It was in bits and I collected all I could find and put it together as best I thought. I wouldn't mind having a go with it now and want to confirm the correct placement of the glass and the spacer. I found this description from 'goamules' https://www.largeformatphotography.info/forum/showthread.php?105539-Magic-Lantern-Projector-Lenses&p=1121784&viewfull=1#post1121784
and wondered if this is the way to go with mine?
Thanks for any help.
https://live.staticflickr.com/65535/53048287378_e04ef02147_c.jpg (https://www.flickr.com/gp/ajmillerphoto/CcgJ7uP3nh)001 (https://www.flickr.com/gp/ajmillerphoto/CcgJ7uP3nh) by Tony Miller (https://www.flickr.com/photos/ajmillerphoto/), on Flickr
https://live.staticflickr.com/65535/53048184395_3fb5d4446f_z.jpg (https://www.flickr.com/gp/ajmillerphoto/c2zE52c9g9)003 (https://www.flickr.com/gp/ajmillerphoto/c2zE52c9g9) by Tony Miller (https://www.flickr.com/photos/ajmillerphoto/), on Flickr
https://live.staticflickr.com/65535/53048184405_c3eaa1d336_z.jpg (https://www.flickr.com/gp/ajmillerphoto/7EA1zfcG89)004 (https://www.flickr.com/gp/ajmillerphoto/7EA1zfcG89) by Tony Miller (https://www.flickr.com/photos/ajmillerphoto/), on Flickr
https://live.staticflickr.com/65535/53047798866_6ac2c7980d_z.jpg (https://www.flickr.com/gp/ajmillerphoto/905cpkp8z6)005 (https://www.flickr.com/gp/ajmillerphoto/905cpkp8z6) by Tony Miller (https://www.flickr.com/photos/ajmillerphoto/), on Flickr

[MartyNL]

Hi Tony, Hopefully, all of the pieces are there. I think there is a great probability that the lens is either a Petzval or Triplet design. Please, see images.
The spacer will go between the two closely spaced lens cells, accordingly.

It sounds like a wonder project and it would great to see the results.

[Steven Tribe]

This is perhaps a better drawing. Note the greatest curvature on the double convex lens points towards concave surface - with the spacer between them. The Waterhouse slot has been home cut in a plain projection apparatus.
There is more here https://antiquecameras.net/petzvallens/oldarticle.html.

[ajmiller]

Thanks for the replies Now to sorting the stops out. A friend did make some wooden ones a few years ago but I think the ridge for the rack and pinion was an obstacle in getting a good fit (though I’m unsure that’s a major issue?). All good fun!