QUESTION Have any various windmill designs been trialled?
There are a number of various windmill designs past the normal horizontal axis wind generators (HAWTs) that most individuals are conversant in.
Probably the most generally trialled are vertical axis wind generators (VAWTs). These are available in two kinds. The Savonius rotor, created by Finnish engineer Sigurd Johannes Savonius, incorporates a barrel-like form with two or extra scoops that catch the wind, inflicting the rotor to spin. It is easy, strong, and works effectively at low wind speeds.
Nevertheless, it is much less environment friendly than different designs, together with the Darrieus turbine, which is known as after its French inventor Georges Jean Marie Darrieus. This consists of curved blades that rotate round a vertical axis. Whereas it may possibly function effectively in turbulent wind circumstances, it typically requires an exterior energy supply to begin.
A view of Nutley Windmill within the Ashdown Forest, East Sussex
Apart from HAWTs and VAWTs, there’s a spherical wind turbine: this may seize wind from any path because of its dome form. Kite generators use giant kite-like buildings to harness wind power at excessive altitudes the place speeds are larger and extra constant. Electrical energy is then transferred again to the bottom by way of a tether.
One other design is the windbelt, a small-scale, non-rotating system that generates electrical energy by way of a vibrating membrane (belt).
Paul Harm, Portsmouth
QUESTION Why do the crows in my backyard incessantly go away stones within the hen tub?
That is one thing of a thriller however there are a few theories.
In terms of intelligence, few birds, if any, are smarter than crows. They’ll depend, remedy issues and generally even communicate just a few phrases of English.
It is common for crows to soak meals in water, in all probability to melt it for consumption. So one concept is that crows drop stones in water as a result of they’ve mistaken them for meals akin to a crust of bread or a nut.
One other approach that crows make meals palatable, particularly meals in a tough shell, is to drop it from a peak, inflicting the shell to interrupt and the crow to entry the meals inside.
They have been noticed dropping walnuts, crabs and different shellfish onto rocks so maybe they’re fooled into considering that the mirror floor of the water is a tough floor on which they will crack their meals.
Gill Evans, Harwich, Essex
Pictured is a fledgling hen in a stone hen tub. File photograph
QUESTION What constitutes an empire? What’s considered the smallest empire?
Empire, by definition, is a versatile time period. Typically, nonetheless, it should meet sure circumstances: it’s a political entity that extends its energy over numerous areas and peoples and is usually dominated by a government, akin to an emperor or imperial authorities. It typically conquers or annexes different territories, exercising its legal guidelines over these nations or ethnic teams.
Empires often characteristic a posh administrative construction and a robust army presence, and endeavour to combine or handle the cultural, financial, and political techniques of the areas below their management.
Throughout the nineteenth century, Hawaii described itself as an empire nevertheless it’s questionable whether or not it meets the ethnic variety standards. Likewise, Napoleon Bonaparte was as soon as designated ‘Emperor’ of Elba, however as Elba is the small island off Tuscany the place he was exiled, he was hardly a real emperor.
A greater candidate is perhaps the Empire of Sumer. This was the earliest recognized civilisation (initially settled round 4,500-4,000BC) which managed among the world’s first city-states: Uruk, Eridu, Kish, Nippur, Lagash and Ur.
These all match into a comparatively small area of Mesopotamia (now Iraq) occupying about 0.04 per cent of the Earth’s space.
One other contender is perhaps the Latin Empire or its neighbour, the Empire of Trebizond.
The Latin Empire was established within the early thirteenth century by the leaders of the Fourth Campaign on lands captured from the Byzantine Empire. Centred round Constantinople, it managed elements of Thrace and a few Aegean islands, and laid declare to numerous Balkan states. Nevertheless it survived for lower than 60 years.
The Empire of Trebizond, a rump state of the Byzantine Empire, was situated east of Constantinople alongside the northeastern coast of Anatolia. With its capital in modern-day Trabzon, Turkey, the empire was recognized for its strategic location on the Black Sea, serving as a hub for commerce between Europe and Asia. It existed till the fifteenth century.
S. Okay. Brown, Derby
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