Weather Ball
Variations in barometric pressure are associated with weather systems and these changes are immediately revealed by the water level in the spout. A low level of liquid in the spout indicates high pressure and fair weather can be expected. A high water level is associated with "bad" weather. In cases of severe weather and major storms the water may even run out of the spout.
How it works:
Our atmosphere has weight. This pressure or weight changes with high and low pressure systems associated with weather. When the weather ball is filled, the air pressure in the globe is trapped and held constant. Thereafter, relative changes in air pressure are visible in the spout.
The instruments is sensitive enough to display changes in air pressure in a three story house, the difference in pressure between the basement and the attic is visible.
Galileo Thermometer
When temperature rises, the liquid inside the glass tube becomes less dense and the liquid filled bulbs will sink. When the temperature of the room cools, the process is reverses and the bulbs will rise from the bottom.
How it works:
The temperature is determined by the lowest floating bulb. When the temperature is in the middle, the temperature between that degree and the lowest floating bulb. If all bulbs float to the top, the temperature is under the lowest floating bulb. If all the bulbs are at the bottom, the temperature is over the highest bulb.