Although records dating to the 1700s refer to spring scales for measuring weight, the earliest design for such a device dates to 1770 and credits Richard Salter, an early scale-maker.[1] Spring scales came into wide usage in the United Kingdom after 1840 when R. W. Winfield developed the candlestick scale for weighing letters and packages, required after the introduction of the Uniform Penny Post.[2] Postal workers could work more quickly with spring scales than balance scales because they could be read instantaneously and did not have to be carefully balanced with each measurement.
By the 1940s various electronic devices were being attached to these designs to make readings more accurate.[1][3] Load cells, small nodes that convert pressure (or force) to a digital signal, have their beginnings as early as the late nineteenth century, but it was not until the late twentieth century that they became accurate enough for widespread usage.