Further information about affecting factors...

About sand hourglasses: Learning more about what determines the passing of time, and especially the accuracy of passing time, the factors can be further narrowed to 3 areas of focus - the size of the particle, the size of the aperture the particles move through, and the angle at which the particles slide against the container's wall toward the aperture. The Mechanics of the Sandglass lays out a mathematical formula for determining accuracy. The math focus on these 3 areas and even when approaching the dilemma in a practical, day-to-day fashion, common sense seems to concur.


If the hole is too small for particles to fall through easily, then their descent is slow or perhaps get stuck. Even if one could squeeze through a hole that was just big enough, all the particles would have to be the exact size.  With just one that is too big to easily pass through, there would be a back up.

Left shape - sharp, almost vertical wall
encourages more sand to fall toward the hole whereas
the right flattens out the angle discouraging particle fall.

Another issue concerns the angle of the container wall. As the wall becomes more  horizontal, the particles would have less gravity promoting the descent through the hole. This becomes a problem with hourglasses built from plastic bottles or jars using a horizontal pieces of board or plastic between the two openings with a punctured hole in the middle for the sand to fall through.

Sand Hourglasses - Factors Affecting Accuracy

The Library of Congress explains there are several factors that affect the way an hourglass filled with sand works. Paring down the factors, these are what need to be addressed in the current project of combing hourglasses with gourds:

- amount of sand 

- size and angle of the glass bulbs

- quality of the sand 

- width of the neck

- tight seal 

- level surface

In this project, the hourglasses being used were purchased from a local home furnishings store. They are glass, filled with fine sand, and are sealed shut so moisture cannot get into the glass bulbs to make the sand damp and therefore heavier. 

Historical Evidence of Hourglasses

hourglass on strings

The Guinness Book of Records says the first solid proof of hourglasses were in 14th century ship inventories where devices in which sand fell from one glass globe into another. These are far more accurate on the seas than the earlier clocks made of water since the movement of the seas would make the clock-water move as well.

Earlier time pieces were made using water. These had problems due to atmospheric pressures which made the water flow faster or slower depending on air temperatures and moon cycles.

Welcome to For a Gourd Time...

Welcome to For a Gourd Time.  Exploring hour glasses and gourds can be a challenge because, frankly, what does an hour glass have to do with gourds? Time is passed whether sand sifts through glass or a gourd grows on a vine. What are the possibilities?