Probably you have thought it out and found some solution as I did, but
in case these difficulties are still formidable I will tell you of _one_
way to reduce them to impotence. I take with me, on all occasions where
there is to be great uncertainty of light, some coloured chalks. About
six colours, picked to suit the kind of work attacked; either chalk
pencils or hard pastilles will give you certain colour values in
whatever light you find yourself, and even if you can hardly see what
you are drawing these _must_, to some extent, standardize your values,
so that your rough work can be washed over and brought up to any pitch
of detail subsequently, without danger of the main tones of your sketch
being wrong. The speed with which a sketch can be carried forward in
this way, and the "quality" obtained by the rapid fusion of the chalk
with the colour wash, are both pleasant surprises when experimenting in
this medium.

Night after night we sallied forth and roamed about the narrow ways and
tortuous turnings of old Baghdad. The bazaars are mostly covered in with
arched masonry, and the effect is that of a long side aisle in a very
untidy and greatly secularized cathedral. From time to time glimpses of
the dark-blue, star-filled sky showed through openings overhead, and
sometimes a quaintly framed view of a dome or minaret.

On one occasion we embarked in a goufa, and floated down the rapidly
flowing river, keeping close to the left bank and taking advantage of
every eddy and corner of slack water made by projecting buildings, lest
we should be swept down too far and lose control of our curious and
difficult craft. The level of the water was far above the usual height
and came up to the very thresholds of these riverside houses. We floated
on, sometimes under the walls of dark gardens, sometimes getting
glimpses of interiors--interiors which in this glamour of night romance