"Speaking of the magic lantern in Germany, we are told that Professor Bötcher (Böttcher), of Berlin, Germany, is probably the greatest lantern exhibitor in Europe. For six month in each year, beginning in October, he exhibits in the Royal Tragedy Theatre, enjoying the patronage of the Court. The lanterns are concealed behind the screen (of about 10 square feet), which medium is prepared in a solution that renders it very transparent, and causes it to hold the projections with remarkable clearness. The entertainment is announced as an Instructive Soirée, and is in three parts: 1. Travel in which some one country is beautifully illustrated. 2. Science, introducing the sun, or moon, or microscopic projections. 3. Variety, in which paintings, statuary, dissolving views, etc. are finely presented.
The Professor's pictures are elaborately painted in oil colours, frequently costing from $50 to $125 each, and never being valued at less than $25. This magnificent collection of paintings and the instruments used for projecting them are worth about $40.000, and their use gets the Professor about $7.000 per annum, clear of all expenses.
Professor Böttcher spends his six month of intermission in the preparing of new slides, to add to his already enormous collection; and these new scenes must be of the highest excellence in order to please the critical people of Berlin, who have learned to expect great things at the Instructive Soirée of the Dramatic Theatre Royal." (The Photographic News. August 8, 1879; extract from the Exhibitor of Philadelphia)