"Ulla, ulla, ulla, ulla," wailed that superhuman note--great waves
of sound sweeping down the broad, sunlit roadway, between the tall
buildings on each side.  I turned northwards, marvelling, towards the
iron gates of Hyde Park.  I had half a mind to break into the Natural
History Museum and find my way up to the summits of the towers, in
order to see across the park.  But I decided to keep to the ground,
where quick hiding was possible, and so went on up the Exhibition
Road.  All the large mansions on each side of the road were empty and
still, and my footsteps echoed against the sides of the houses.  At
the top, near the park gate, I came upon a strange sight--a bus
overturned, and the skeleton of a horse picked clean.  I puzzled over
this for a time, and then went on to the bridge over the Serpentine.
The voice grew stronger and stronger, though I could see nothing above
the housetops on the north side of the park, save a haze of smoke to
the northwest.