. Bulletin - United States National Museum. Science. u^:i'-"^ â 'WjH:^ Figure 28.âModel 621 Small Price current meter. Only one contact chamber of the penta type was furnished with these meters when orders specified the 621 model. (Smitlisonian photo 44537-E.) click to occur annoyed the men who used them on field work, the meters soon were provided with two interchangeable contact chambers, the extra one providing an electrical contact at each revolution. At first, these extra contact chambers vfcre con- structed like those on the early 618 models, with two binding posts, one for the insu
. Bulletin - United States National Museum. Science. u^:i'-"^ â 'WjH:^ Figure 28.âModel 621 Small Price current meter. Only one contact chamber of the penta type was furnished with these meters when orders specified the 621 model. (Smitlisonian photo 44537-E.) click to occur annoyed the men who used them on field work, the meters soon were provided with two interchangeable contact chambers, the extra one providing an electrical contact at each revolution. At first, these extra contact chambers vfcre con- structed like those on the early 618 models, with two binding posts, one for the insulated wire and tlie other for the ground (see figures 24 and 29). On later models, however, the single-point chamber was made to correspond with the penta chamber in its outward appearance. In Gurley's catalog, the number 624 was assigned to meters that had been fiunishcd with the two contact chambers. All model 624 meters used by the Survey were rated twiceâa low-velocity rating for use with the contact chamber that produced one electrical contact per revolution and a high-velocity rating for use with the penta-contact chamber. For field purposes, both ratings usually were combined in a single rating table. To introduce the 621 model, J. C. Hoyt prepared an article for the Engineering News entitled "Recent Changes of Methods and Equipment in the Water Resources Work of the Geological Survey," which was published on July 2, 1908. In that article Hoyt wrote that it was: ... a meter that can be readily carried in the field and manipulated by one man under all conditions of velocity, depth, and width of a stream and with the various facilities for making measurements, which can be either a bridge, a boat, a cable and car, or by wading. A further description of the meter was contained in a paper entitled "The Use and Care of the Current Meter as Practiced by the Geological Survey" that Hoyt presented before the American Society of Civil Engineers on
Size: 2947px × 848px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorun, bookcentury1800, bookdecade1870, booksubjectscience
