Lead Collimator Slit, by H.G.J. Moseley?, Manchester/Oxford c.1913

This piece of apparatus is attributed to Henry Moseley and was probably used by Moseley, first at Manchester in 1913 and then at Oxford from November 1913 to the summer of 1914. He studied chemical samples using X-ray spectroscopy and hence determine their atomic number. The results were published in the ‘Philosophical Magazine’ in 1913 and 1914.

A collimator slit is an essential part of any spectrometer, as it restricts the input beam of particles or waves so as to produce sharp spectral lines. They were a feature of all Moseley’s experiments on X-rays, from his diffraction studies with Charles Garlton Darwin in Manchester from November 1912 onwards to his own definitive spectroscopic experiments conducted in 1913 and 1914. Moseley mostly used a lead collimator slit like this one but sometimes replaced it with a platinum collimator slit.

See attached narrative 'Henry 'Harry' Moseley and his experiments' for further details.