418 On the Cyclones of Tasmania, ce. 
effects. ‘These winds occur three or four times every sum- 
mer, and continue from 24 to 86 hours. They blow from 
the north-westward, causing the thermometer to rise to up- 
wards of 100° F., and are succeeded almost instantaneously 
by a violent southerly wind, which lowers the temperature 
so rapidly that the thermometer has been known to fall 25° 
in 20 minutes. Their arid parching nature not only injures 
the fruit and crops, but leaves the timber and herbage an 
easy prey to the “bush fires” which prevail, whether by 
accident or design, during the summer months. 
The most fearful and destructive visitation of this kind 
occurred on Thursday, the 6th February, 1851—a day ever 
since distinguished in the Australian calendar as “ Black 
Thursday.” The loss of life was serious, but the loss of 
property was immense and extensive. The fires swept over 
a tract of country of upwards of 600 miles in length. A 
few abridged extracts from the newspapers of the period will 
show the nature of this fiery tempest, both on land and at 
sea. 
The most striking features of the Cape Otway country 
are, the immense size and crowdedness of the timber trees, 
and the density and luxuriant growth of the fern scrub. 
This scrub, in ordinary circumstances, burns slowly ; while 
a fire may continue for weeks in some parts of the ¢imber 
without extending far. Such a fire was, in fact, known to 
have existed for.a month past in the mountain ranges, but 
no alarm was felt in consequence. The hot blast of ‘Thurs- 
day, however, playing upon the kindled nucleus, caused the 
fire to spread with such fury that the dense scrub was swept 
away like stubble, and the flames were carried along the tops 
of the trees, leaving the massive trunks ignited wherever 
any decayed, hollow, or dead branch gaye the fire a nestling 
place. 
