  For an inhomogeneous high-T_c superconductor, band-filling dependence of
Josephson current and Josephson product is deduced at T=0 K by means of
measurement; this is an extension of Ambegaokar-Baratoff Josephson current and
product. The observed Josephson current, J_{obs}, is given by
J_{obs}={\rho}J_i, where 0<\rho<=1 is band filling (or local density). When
\rho=1, J_{obs} = J_i is the intrinsic supercurrent occurring by Cooper pair.
When 0<\rho<1, J_{obs} is an average of J_i over the measurement region and is
the effect of measurement. The observed Ambegaokar-Baratoff Josephson product,
based on the s-wave theory, is given by J_{obs}R_n
=({\pi}/{2})(\rho\triangle_i), where \triangle_i is the intrinsic
superconducting gap and small, which results in small Josephson products
observed by the experiments. The intrinsic gap, 4<{\triangle_i}<10 meV, is
analyzed from the Josephson-product data of BSCCO. In addition, the
triple-{\pi}-junction experiments, observing the half-flux quantum ({\Phi_0}/2)
as evidence of d-wave symmetry, are discussed by using means of measurement.
Comments on a flux trap of the magnetic modulation experiment using Pb-YBCO dc
SQUIDs are also given. Author's thought is given on the angle dependence of
$J_c$ measured in whisker.
