Lot of 4 ashtray’s measuring typically 5”x5” from the early 1900’s. First ashtray has title “The Pedro Play – Where Is The Fourth Man” and shows three men playing cards with empty fourth chair. The reverse of ashtrays has image showing man in bathroom with text “Solo!!!” which is only visible when viewed in reflected light. The second ashtray has text “Coming Through The Rye,” and shows European Military Officer seducing women in field with reverse image showing their feet sticking out from field, and is only visible in reflected light. Both made in Germany. Third and fourth ashtray’s are souvenirs from Niagara Falls and feature same “invisible” reverse images. First tray in pair shows trio peeping through hole with text “What Kind Of Surprise Curious Peepers Have At A Keyhole.” Reverse shows man & bare breasted women embracing. Last ashtray shows housewife with text “The Mistress Cries: Where Can Be My Husband And Where My Maid?” Reverse shows maid and husband involved in a dog house. All reverse “invisible” images have some wear, but are still visible when viewed in reflected light. First two in lot have some scattered wear to images and second has 30% of gold accent luster remaining. Exc. Third & fourth trays in lot have some wear from use to images and text. VF. An interesting and early risqué novelty.