34 REPORT—1848. 
River, the whole of her hull being visible. As we passed on the image retained its 
position for some time, but vanished when we came to a turn of the road. 
On arriving at a point where I could look down the river, [ saw within about 150 
yards of the sand-hill above referred to a schooner lying dry, which was evidently 
the vessel we had previously observed. She was much out of the proper channel, 
but had gone ashore by accident and remained there many weeks. The top of her 
masts was below the level of the sand-hill, so that her picture was thrown up more 
than the height of her masts. 
The weather was cold, with a strong north-easterly wind and a bright sun; the 
schooner lying under the sand-hill, protected from the wind and in the full sunshine, 
which was powerful for the season. Two very different conditions therefore ob- 
tained in the atmosphere at that place; the air immediately surrounding the vessel 
being warmed by the sun, not under the influence of the wind, and probably charged 
with vapour evaporating from the wet sand; while the air above the level of the 
sand-hill was rapidly changed by the keen, frosty wind, and must have been of a 
very different temperature and density. 
The other phenomenon to which I would direct attention occurred about nine- 
teen years ago, and was witnessed by many most respectable parties, among others 
by the then vicar of Swansea, the late Dr. Hewson. The whole promontory 
of the Mumbles was seen reflected in the sky, so that at the same time the true 
image and the counterfeit were visible. There was a width of sky seen between the 
two of a breadth about equal to the height of the Mumble rocks, and the refracted 
image was a correct copy of that below, except that the perpendicular objects—as 
the lighthouse—were somewhat too tall, and became still more so before the disap- 
pearance of the illusive image, which was observed during about ten minutes. 
Observations accompanying Wind and Current Charts of the North Atlantic. 
By Lisut. Maury, U.S. Navy. 
[A Letter addressed to Prof. H. D. Rogers, by whom it was communicated to the Association. ] 
National Observatory, Washington, July 10, 1848. 
These charts are offered not for what they are, but for what they may be. They 
are a mere first attempt, a rough beginning, incomplete and faulty, by reason of the 
very defective materials used in their construction. They are compiled from abs- 
tracts of old sea logs kept without order, system or arrangement. Some are with- 
out record as to current, temperature or variation; and others are faulty in many 
respects. But it was found necessary to make a Jeginning in order to attract the 
attention of navigators to the subject, and so procure labourers for the field; and 
this these charts have succeeded in doing, in this country at least. 
Every navigator who will apply, is furnished gratis with a set of them and with a 
blank form, for recording results of the requisite observations. And though but a few 
weeks have elapsed since the publication of these charts, such has been the eager- 
ness of navigators to procure each his copy, and such their readiness to contribute 
the requisite data for a mere complete set, that fleets of ships are now engaged in 
all parts of the world (as they go to and from across the sea), in making and record- 
ing all—by a prescribed form—the necessary observations. 
I have secured the co-operation both of the military and commercial marine of 
the United States, and before the end of the year, probably, not less than a thousand 
vessels will be collecting materials for the completion of these charts. Could the 
vessels of Great Britain be engaged in like manner, the value of the results would be 
greatly enhanced, because then we should probably have vessels enough engaged to 
afford synchronous observations for the space of a year, or longer, should it be — 
desired, of the winds, currents, temperature of the ocean, &c. in all parts of the world. 
The plan is, to construct similar charts of the three great oceans, to lay down the 
tracks of all the vessels engaged, in colours according to the season. Thus the 
tracks in winter will be all black; those in spring, green; in the summer, red; in 
the autumn, blue. Each track has marked on it, in such a manner as to show at 
once the daily experience of the navigator who made it, the winds, currents, tem- — 
perature of the water, variation of the compass, &c.; thus placing at a glance before — 
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