Residuals in the latitude observations by the US Naval Observatory at Washington in the years 1932-1991 are analyzed. They are shown to be correlated with the southern oscillation index (SOI) in the interannual frequency range, with correlation coefficients as high as 0.6-0.7 or greater. The PZT residuals lag behind the SOI by some 2 years. This is probable evidence that variatons in the plumb line in land areas are connected with large-scale motions of the oceans and the atmosphere.