In some localities, householders are provided with "wheelie bins" for garden waste.
These bins have a hinged lid.
If a bin is filled with fresh cut grass, and the lid is left propped open with a stick, on a sunny day* the bin heats up and much moisture evaporates, causing the contents to shrink and allowing more material to be loaded.
But if it rains**, the rain wets the cuttings and accumulates in the bin. Not good.
BorgCo engineers have developd an automatic bin-closer to prevent this problem. The device consists of a wooden lath, at the end of which is a mechanism resembling a mousetrap. This is prevented from operating by a soluble aspirin tablet, above which is a small funnel.
When it rains, water is collected by the funnel and dripped onto the aspirin, which dissolves. The spring is released and the arm flips the lath clear of the bin, allowing the lid to fall shut under the influence of gravity***
*Readers in the UK may not be familiar with this. **Readers in the UK will definitely be familiar with this. ***Gravity not included.-- 8th of 7, Jun 15 2015 Wheelie bin https://en.wikipedi...tainer#Wheelie_binsUgly doesn't come close. [8th of 7, Jun 15 2015] Sounds like a headache to deal with.-- AusCan531, Jun 15 2015 [+] A bun for an image of an interesting contraption. I hope no one sneaks up and substitutes an insoluble aspirin.-- cudgel, Jun 15 2015 Sp.: Sinsetive-- MaxwellBuchanan, Jun 15 2015 The average mousetrap is triggered by sudden change, more than by gradual change. Has this device actually been tested?-- Vernon, Jun 16 2015 /Has this device actually been tested/
What, and leave the comforts of the armchair?
It occurs to me that a horizontal lid could accomplish rain protection and ventilation both. Like on the porch.
What if the aspirin gets mushy from the verdant humidity coming off your mulch?-- bungston, Jun 17 2015 //Has this device actually been tested//
No.
<SNAP>
OUCH !
Yes.-- 8th of 7, Jun 17 2015 random, halfbakery