Given information:
- A ball is projected from the ground at an angle theta with the horizontal.
- After 1 second, the ball is moving at an angle of 45 degrees with the horizontal.
- After two more seconds, the ball is moving horizontally.

To find:
The angle of projection of the ball.

Solution:
Let's break down the problem step by step.

Step 1: Analyzing the first second of motion
- After 1 second, the ball is moving at an angle of 45 degrees with the horizontal.
- This means that the vertical component of velocity is equal to the horizontal component of velocity.
- Let's assume the initial velocity of the ball is 'u' and the angle of projection is 'θ'.
- So, after 1 second, the vertical component of velocity is 'u*sin(θ)' and the horizontal component of velocity is 'u*cos(θ)'.
- Since the vertical component of velocity is equal to the horizontal component of velocity, we have:
u*sin(θ) = u*cos(θ)
tan(θ) = 1
θ = 45 degrees

Step 2: Analyzing the next two seconds of motion
- After two more seconds, the ball is moving horizontally.
- This means that the vertical component of velocity is zero.
- Let's assume the final velocity of the ball is 'v' and the angle of projection is 'θ'.
- So, after 3 seconds, the vertical component of velocity is 'v*sin(θ)' and the horizontal component of velocity is 'v*cos(θ)'.
- Since the ball is moving horizontally, the vertical component of velocity is zero.
v*sin(θ) = 0
sin(θ) = 0
θ = 0 degrees

Step 3: Conclusion
- From Step 1, we found that the angle of projection after 1 second is 45 degrees.
- From Step 2, we found that the angle of projection after two more seconds is 0 degrees.
- The angle of projection of the ball changes from 45 degrees to 0 degrees between the first and third seconds.
- Therefore, the angle of projection of the ball is 0 degrees.

Answer:
The angle of projection of the ball is 0 degrees.