Supersonic shock waves, Schlieren image
Supersonic shock waves. Schlieren image showing the shock wave created by a supersonic jet flying in front of the Sun. Schlieren imaging is a method used to visualise density variations in transparent media. Here, it has been used to view the propagating disturbance in air created by an aircraft moving at the speed of sound. The method requires a bright light source and/or speckled background. In this case, the solar disc has been used, a technique called Background-Oriented Schlieren using Celestial Objects (BOSCO).
© NASA/SCIENCE PHOTO LIBRARY
China - Christian Clergyman Rev. John Kao (Shantung Diocese)
China - A superb portrait of Clergyman Rev. John Kao (Shantung Diocese). The S.P.G. (Society for the Propagation of the Gospel in Foreign Parts) sent its first missionary to China in 1863 Date: circa 1910s
© Mary Evans / Grenville Collins Postcard Collection
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Workhouse inmate 'Mary Jane' promoting charitable work
A postcard promoting the work of the Society for the Propagation of the Gospel in Foreign Parts (SPG). Its caption reads 'Mary Jane, who is a deaf and blind inmate of a Workhouse in Devonshire, was the means of starting the Candidates' Five Shilling Fund in connection with the S.P.G.' She is shown sitting at a table, reading by touch (probably from Braille).
© Mary Evans Picture Library 2015 - https://copyrighthub.org/s0/hub1/creation/maryevans/MaryEvansPictureID/10472655