An hourglass, also called a sand clock, is a device for measuring time.

A typical hourglass is filled with sand and once all the sand has flowed to the bottom glass ball, the hourglass can be turned upside down to measure the time now and the typical hourglass has a nominal running time of 1 minute.

Factors that affect the time hourglass include: the amount of filler, the shape of the curve of the inside of the glass ball (there is a slight difference in the timing length between the hourglass forward and upside down), the width of the neck tube, and the type and quality of the filler.

Hourglasses can also be made at home by yourself.

1.Find two beverage bottles of the same height, remove the two caps, drill three small symmetrical holes in the same orientation on the two caps, fix the two caps back to back with screws.

Then drill a larger hole in the middle of the two caps as a sand leak hole.

2.To the site to fill two bottles of clean fine sand back, dry spare.

3.Find a screen mesh, make a small sieve, the coarse point of sand sieve out, leaving fine sand, such as sand is not fine enough, sieve on the pad two or three layers of sand mesh cloth.

Then sieve a weave, leaving a finer sand.

4.The sieve out of the fine sand filled one of the bottles, and then tighten the lid of the bottles together.

Then the empty bottle is also filled up.

Simple hourglass timer is ready!

5.The bottle upside down, so that the bottle filled with sand on top, you can see the fine sand from the hole in the middle of the cap to the bottle below, such as sand leak a little card.

Then the hole to increase the sand leak a little more, until the sand leak is very smooth.

Hourglass timer is done, the following will use it to measure the time.

The hourglass timer upside down when you start timing, look at the full bottle of sand all leak to the bottle below to a few minutes, the timing process, respectively, in the location of each minute sand leak down with an oil-based pen for a mark.

In use when you see the sand to this position will know how long it has passed.

The most famous hourglass is the "five-round hourglass" created by Zhan Xi Yuan in 1360.

The sand flows from the funnel-shaped sand pond to the sand hopper on the side of the primary wheel, which drives the primary wheel, thus driving the mechanical gears at each level to rotate.

The last gear drives the middle wheel which rotates on the horizontal plane, and there is a hand on the axis of the middle wheel, and the hand rotates on an instrument disc with an engraved line.

So as to display the time, and this display method is almost identical to the surface structure of modern clocks.

In addition, Zhan Xiyuan also cleverly added a mechanical toggle device on the middle wheel to remind the two wooden men standing on the five-wheel hourglass to beat the drum to tell the time.

At each full hour or moment, the two wooden figures would come out by themselves and beat the drum to report the moment.

This hourglass was detached from the auxiliary astronomical instruments and had become a mechanical clock structure on its own