為什麼Singapore Zoo內的獅子老虎鹿全不是在籠內

A sunken ditch is used instead of fences... it is a device called 'ha-ha' which was invented in English garden design. You can refer to the following extract from Wikipedia:


The ha-ha or sunken fence is a type of boundary to a garden, pleasure-ground, or park, designed not to interrupt the view and to be invisible until closely approached. The ha-ha consists of a trench, the inner side of which is perpendicular and faced with stone, with the outer slope face sloped and turfed - making it in effect a sunken fence. The ha-ha is a feature in the landscape gardens laid out by Charles Bridgeman, the originator of the ha-ha, according to Horace Walpole (Walpole 1780) and by William Kent and was an essential component of the "swept" views of Capability Brown.

"The contiguous ground of the park without the sunk fence was to be harmonized with the lawn within; and the garden in its turn was to be set free from its prim regularity, that it might assort with the wilder country without. " — Walpole, "Essay upon modern gardening"

Walpole was unaware that the technical innovation had been presented in Dezallier d'Argenville's La theorie et la pratique du jardinage (1709), which had been translated into English by the architect John James (1712):

"Grills of iron are very necessary ornaments in the lines of walks, to extend the view, and to shew the country to advantage. At present we frequently make thoroughviews, call'd Ah, Ah, which are openings in the walls, without grills, to the very level of the walks, with a large and deep ditch at the foot of them, lined on both sides to sustain the earth, and prevent the getting over; which surprises the eye upon coming near it, and makes one cry, Ah! Ah! from whence it takes its name. This sort of opening is, on some occasions, to be preferred, for that it does not at all interrupt the prospect, as the bars of a grill do."

Most typically ha-has are still found in the grounds of grand country houses and estates and act as a means of keeping the cattle and sheep in the pastures and out of the formal gardens, without the need for obtrusive fencing. They vary in depth from about 2 feet (Horton House) to 9 feet (Petworth).

Walpole surmised that the name is derived from the response of ordinary folk on encountering them and that they were, "...then deemed so astonishing, that the common people called them Ha! Ha's! to express their surprise at finding a sudden and unperceived check to their walk."

A more recent use of a ha-ha is at the Washington Monument to minimize the visual impact of security measures.

錯啦!!!!係因為果d係safar park,so可以比佢地出泥!!!!明未?死假膠!!!又唔知,係到扮晒野咁!!!

Wild zoo 野生動物園是將動物放在一個特定範圍, 不用細少的籠去困著動物, 讓牠們好像生活在一個野生世界內, 其實牠們都仍然被圍欄圍困著, 只是這個欄比較大了點. 所以不怕他們走出來的