Measurement and Control

Casimir, H. B. G.

doi: 10.1177/002029407701000701pmid: N/A

doi: 10.1177/002029407701000702pmid: N/A

Sydenham, P. H.

doi: 10.1177/002029407701000703pmid: N/A

Measurement hardware before the 19th century is reasonably well reported in historical works. More modern electrical devices have not been studied as extensively, presumably because of the high degree of understanding needed of the historian and because the artifacts and written information are not easy to locate.This article provides a brief summary of the history of sensing, a working guide to dominant world collections of sensing apparatus, and an introductory guide to the literature available on sensing methods. It is intended as an aid to historical sensing technique research.

Liovin, A. A.

doi: 10.1177/002029407701000704pmid: N/A

Belforte, G.; Piombo, B.

doi: 10.1177/002029407701000705pmid: N/A

A new timing system for a water treatment chemical plant is introduced here. The purpose of this system is to permit the inlet of sodium hypochlorite for 20 min at a time interval variable from 2 to 6 h. The problem is solved by a fluidic-mechanical equipment utilising as power source the same water circulating in the plant. For this purpose suitable hydrofluidic elements have been studied, and their performances are presented. Then the timing system, designed with a mechanical spring timer and two memory hydrofluidic components, is described. The spring timer drives thin plates which operate some hydrofluidic sensors; these sensors control the two memory hydrofluidic components. The first fluidic element controls the inet valve of the hypochlorite; the second element reloads the timer at the end of the cycle