ON THE FLIGHT OF BIRDS. 249 
to sweep on their way to the slaughter-houses and more popu- 
lous parts of Simla, where they mostly resort during the day. 
A large colony of Vultures and several pairs of Lammergey- 
ers always roost and breed in some nearly inaccessible cliffs at 
the back of the Mahassu range, the crest of which may be 
distant about four miles, as the crow flies, from the Jacko preci- 
pices already referred to. It is the denizens of this colony 
whose “march past” I almost daily observe from a_ recess 
about half way down the slope, along which, often within five 
yards of the cliff, the birds sweep, one after the other, en 
route to their breakfasts. 
On fine summer mornings the birds begin to pass between 
six and seven o’clock, but on cold winter days, especially on 
cold wet days, they will not appear till nearly 9 a.m. From 
where I sit, I can, on bright mornings, with a glass, clearly see 
them as they top the Mahassu ridge, and thence observe their 
whole course until they pass me and for from one to two miles 
after they have passed me. 
Now it often happens that one of the Vultures comes the 
whole way from the Mahassu ridge to my nest, and passes 
thence southwards, out of sight, a distance of at least five, 
and often six miles, without having made, during the time it 
was in sight, a single movement of the wings, or more than 
three or four gradual shifts of the tail when slightly altering 
its course. 
Wishing to ascertain the velocity with which they pass—a 
velocity which varies very greatly—I put up two posts on two 
projecting points right and left of my seat, and somewhat 
further out. I then, for several mornings, noted the times of 
each bird’s passing each post, and approximately the distance 
at which each passed outside the posts, and then having pre- 
viously ascertained all the sides of my fixed triangle, of which 
my own position was the apex, while the two posts marked the 
basal angles, it was of course easy to calculate the actual 
length of that portion of the Vulture’s path visible to me be- 
tween the two posts. 
The Vultures, as a rule, slacken speed a good deal in passing 
my precipice. This faces the east, and is very warm and 
pleasant in the mornings, and commands a vast view down a 
deep valley, and not unfrequently, when I have come up a 
little later than usual, I have found several Vultures, and once 
or twice a Lammergeyer, sunning themselves on the ledges. 
So I suspect they slacken speed, intending, if the coast be clear, 
to alight and enjoy the warm sun awhile before continuing 
their matutinal cruise for a meal. 
Well, I found that between seven and eight miles an 
hour was the lowest speed at which any. Vulture passed 
