1. Obtain a barometer: A barometer is a device used to measure atmospheric pressure. It consists of a glass tube filled with mercury or another liquid, with the open end of the tube placed in a container of the same liquid. The height of the liquid column in the tube is affected by the atmospheric pressure, with a higher pressure resulting in a higher liquid column.

2. Measure the barometric pressure at the base of the tower: Use the barometer to measure the atmospheric pressure at the base of the tower. Record this measurement in millimeters of mercury (mmHg) or inches of mercury (inHg).

3. Measure the barometric pressure at the top of the tower: Climb to the top of the tower and use the barometer to measure the atmospheric pressure at the top. Record this measurement in millimeters of mercury (mmHg) or inches of mercury (inHg).

4. Calculate the height of the tower: Assuming a standard atmosphere and neglecting other factors, you can calculate the height of the tower using the following formula:

```

Height of tower (h) = (P1 - P2) * [ (10.342) / (273 + t) ]

```

where:

* h is the height of the tower in meters (m)

* P1 is the barometric pressure at the base of the tower in millimeters of mercury (mmHg)

* P2 is the barometric pressure at the top of the tower in millimeters of mercury (mmHg)

* t is the average temperature in degrees Celsius (°C) during the measurement

Remember that this method assumes standard atmospheric conditions and may not provide precise results in all situations.

Using a trigonometric method:

1. Choose a distant observation point: Select a location that is a significant distance away from the tower (ideally several hundred meters) with a clear line of sight to the top.

2. Set up a tripod and mount a theodolite: Place a tripod at the observation point and mount a theodolite (or a surveyor's transit) on it. A theodolite is a precision instrument that allows for accurate angle measurements.

3. Measure the angle from the horizontal to the top of the tower: Point the theodolite towards the top of the tower and measure the angle (θ) between the horizontal line of sight and the line of sight to the top of the tower. Record this angle in degrees, minutes, and seconds.

4. Measure the distance from the observation point to the base of the tower: Use a measuring tape or a laser rangefinder to measure the horizontal distance (d) between the observation point and the base of the tower. This distance should be measured precisely.

5. Calculate the height of the tower: Use trigonometry (specifically, the tangent function) to calculate the height of the tower (h) using the measured angle (θ) and the measured distance (d):

```

Height of tower (h) = d * tan(θ)

```

where:

* h is the height of the tower in meters (m)

* d is the distance from the observation point to the base of the tower in meters (m)

* θ is the measured angle between the horizontal and the line of sight to the top of the tower in degrees

This method is more accurate if you have a clear, unobstructed line of sight from the observation point to the top of the tower.