Transparent or hold to the light Victorian calling card.

This is the second Victorian hold to the light, transparent or comic card that I have found. We have an old family bible that we recently had restored. We knew we had one of these cards in the bible but on looking at the book a bit more we found a second one tucked in the pages. At first glance the card looks like the first picture. When you hold it to a light you see the hidden image that is shown in the second picture. This one appears to be cut off a bit...but you get the idea. I'm not sure how these are made but it appears that the image is sandwiched between the layers of paper. The color is a bit off on the second image because of the way I scanned it.

I've also done a bit of a research. I believe this card is from John R. Becker that lived in Reading, PA around 1870 and 1880. He is shown in the Reading PA census for those times and was a railroad conductor. My great grandfather, who owned the bible this card was found in, also lived in Reading at the time and worked for the RR as a watchman.