Abstract: Suspended particulate matter in the atmospheric air is sucked into a container by a pump. The suspended particulate matter in the atmospheric air in the container is electrically charged so as to electrically collect it. The collected suspended particulate matter is irradiated with laser beams under the condition that the collected suspended particulate matter is dispersed at an appropriate concentration. A spatial intensity distribution of diffracted and scattered light obtained by irradiating laser beams to the suspended particulate matter is measured. A particle size distribution of the suspended particulate matter P is found from the result of measurement.

Abstract: Suspended particulate matter in the atmospheric air is sucked into a container by a pump. The suspended particulate matter in the atmospheric air in the container is electrically charged so as to electrically collect it. The collected suspended particulate matter is irradiated with laser beams under the condition that the collected suspended particulate matter is dispersed at an appropriate concentration A spatial intensity distribution of diffracted and scattered light obtained by irradiating laser beams to the suspended particulate matter is measured. A particle size distribution of the suspended particulate matter P is found from the result of measurement.

Abstract: In a top scale balance which has a Roberval's chain 10 and a load weight transmitting lever 30 and in which a movable post 13 of the Roberval's chain 10 is connected to a point of force 32 of the lever 30 through an elastic connection fulcrum 51, a horizontal member 12 nearer to the elastic connection fulcrum 51, out of upper and lower horizontal members 11, 12 of the Roberval's chain 10, is greater in rigidity than the other horizontal member 11. Alternately, the upper and lower horizontal members 11, 12 are equal in rigidity and the elastic connection fulcrum 51 is positioned, in the vertical direction, at the center between the upper and lower horizontal members 11, 12. Such an arrangement prevents or reduces the movement of the elastic connection fulcrum 51 in the back-and-forth direction due to an offset placed load. Thus, even though the top scale balance is made in a compact and thin design with the lever ratio increased, the top scale balance is high in precision with a less offset position error.