Let's assume that the height of the tower is `h` meters. Since the man is standing 40 m from the foot of the tower and observes the angle of elevation of the tower to be 30 degrees, we can use trigonometry to find the height of the tower. We can draw a right triangle with the man, the foot of the tower, and the top of the tower as its vertices. The side opposite to the 30-degree angle is `h`, and the side adjacent to it is 40 m. Therefore, we can write:

\(\tan(30) = \frac{h}{40}\)

Solving for `h`, we get:

\(h = 40 \times \tan(30) = 40 \times \left(\frac{1}{\sqrt{3}}\right) = \left(\frac{40}{\sqrt{3}}\right) \times \left(\frac{\sqrt{3}}{\sqrt{3}}\right) = \frac{40 \times \sqrt{3}}{3}\)

So, the height of the tower is \(\frac{40 \times \sqrt{3}}{3}\) meters.