100 YEARS AGO

An ingenious machine for printing in colours, invented by Mr. Ivan Orloff, chief engineer and manager of the Russian Government printing works at St. Petersburg, has just been set up in London, and a company has been formed to develop the use of the machine for supplying coloured illustrations for periodicals and books. In colour printing by the ordinary method the successive colours are applied one at a time as the preceding one becomes dry. By means of the Orloff machine the whole of the colours required in a picture are printed at a single turn of the cylinder. If the picture has to be printed in, say, four colours, four separate blocks are arranged around the curved surface of the cylinder. As each block passes a particular point, the roller carrying the colour required by the block is made to fall upon it by a system of cams. Each block thus receives the coloured ink intended for it in the course of a revolution of the cylinder⃛. The results are very effective, and the “register” is perfect, no matter how many colours are used. The machine appears to mark a distinct development of methods of printing in colours.

From Nature 27 July 1899.

50 YEARS AGO

Luminous night clouds were observed in the northern sky in Scotland on the nights of July 9-10 and July 10-11, the extensive display showing characteristic wave structure in the early morning of July 11 being quite magnificent. Brilliantly blue-white in colour, the night clouds appeared about half an hour after sunset in a sky almost clear of normal cloud, were most brilliant during the hour after midnight and faded in the growing light before sunrise⃛. These rare clouds, which are observed only in summer and in middle latitudes, were first studied by Jesse and later by Störmer using his auroral network⃛. Occurring at heights of about 80 km., they provide valuable information concerning air movement at that level. On the evidence of their colour, it is generally believed that they consist of fine dust of cosmic or volcanic origin. It is significant that the present manifestation followed by a few days after an eruption in the region of the Canary Islands.

From Nature 30 July 1949.