Ib Andersen’s 1927 drawing shows five lighting models from Poul Henningsen’s System PH (illustrated). Henningsen devised this ingenious, rational system to maximise the light produced by an incandescent bulb, with a series of shades—either glass or metal—that could be interchanged according to the demands of the lighting task at hand. Louis Poulsen’s 1927 catalogue of PH lamps advised on which configurations were best suited for particular circumstances, recommending, for example, a matte glass shade on the bottom to spread light over a large area and other arrangements for particular effects of shadow and colour. Henningsen developed this system, which included the present standard lamp (lot 10), the ceiling light (lot 33) and the table lamp (lot 50) before he went on to develop more complex models such as the ‘Spiral’ ceiling light (lot 13) and the counter-balanced ‘Piano’ lamp (lot 19).