images provided for illustrative purposes only
Original Porton Globes and Circles
Eyepiece Reticle with central Rectangle and Globes/Circles
NG2
£133.59 - £156.69
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The circle areas of the Porton reticles increase with Root 2 progression as do the divisions on the right hand side of the rectangle. These divisions are numbered for convenience. Rectangle size is 4.5mm x 2.025mm. The specimen is racked on the mechanical stage of the microscope and traverses are taken right across the deposit sizing all the particles encountered.
Reference: K.R.May, Journal of Scientific Instruments Vol. 22 Oct 1945. “The Cascade Impactor.” An instrument for sampling coarse aerosols.
Soda Lime 1.5mm thick
+0/-0.1mm
Correct reading through glass