The accuracy of these two instruments depends on different things. For the first one it
depends on the linearity and calibration of the spring, whilst for the second it relies on the
calibration of the weights. As calibration of weights is much easier than careful choice and
calibration of a linear-characteristic spring, this means that the second type of instrument will
normally be the more accurate. This is in accordance with the general rule that null-type
instruments are more accurate than deflection types.