Abstract: A linear filter-type sampling device for pneumatic particulates such as air and/or gases, (sometimes referred to as streaker), wherein a series of at least two complementary samples are taken concurrently with time and size particle information. The device is adapted to deposit on a suitable collector for each sample either a continuous uninterrupted streak of matter or a streak of discrete deposits of matter. A unique feature of the sampling device is achieved through the use of a low pressure vacuum chamber through which a stream of aerosol continuously flows, said chamber having a fixed collector paired with a rotatable orifice at its inlet and operating in series or cascade with a rotatable collector paired with a fixed orifice at its outlet, and wherein each pair cooperates with its respective inlet or outlet to preserve the flow of air through the succeeding sampling stages with no gain or loss to the external air surrounding the sampler.