We start reading and display the data:
library (UsingR)
data(galileo)
g2=galileo$init.h-500
gl=galileo$h.d
par(bg='cornsilk')
plot(gl,g2,pch=20,col="red",cex=2,ylim=c(O,1000))
Looking at the data, is it reasonable to look for an affine relation between the variables h. d and init .h?