If you say how much it curves?
And what happens to matter or light in the presence of that curvature?
Calculate it, make the prediction.
If the prediction doesn't come true you don't go and say "okay,
let me see if I can tweak the theory." Not in this case.
You can see on his pages the kind of labor that Curtis had to endure in order to make these measurements.
It's page after page after page of this.
Some page is crossed out.
All you need is one experiment to show that any aspect the relativity would fail and he would have to go back to the drawing board completely.
Curtis looks at the stars and sees nothing unusual.
They all appear in their normal places which can only mean one thing:
Einstein is wrong.
But Campbell is unwilling to risk his reputation on improvised equipment.
Nobody wants to reveal an answer until everything has been double checked.