the resistance of the selenium will be affected by vibration of the mirror. If, then, the mirror be used as a transmitting diaphragm, like that of a telephone transmitter, words spoken to the mirror will be repeated by a telephone in the circuit of which the selenium, is placed and through which an electric current is kept flowing.

In this address an attempt has been made to sketch very briefly the development of the application of electricity to the transmission of intelligence. Many important applications (as, for example, fire-alarms and railway signal systems, etc.) have not been referred to, and a host of important contributors have, as a matter of necessity, been entirely ignored. To go into detail and do justice to everyone who has contributed to the present state of the electric telegraph was an impossibility and has not been attempted.

H. Mis. 114—42

EXPLORATIONS IN MONGOLIA AND TIBET.

BY W. WOODVILLE ROCKHILL.

On the 1st of December, 1891, I left Peking for a journey in Mongolia and Tibet, proposing, if possible, to traverse the latter country from north to south and reach British India-Sikkim or Nepal.

I was well provided with scientific apparatus, and very scantily with money, and so I started out with the anticipation of having to endure many discomforts, and possibly see my chance of ultimate success lost for want of a few hundred dollars and my collections poor for lack of funds and means of transportation. This is the one insurmountable difficulty a traveller can have to contend with; nearly every obstacle can be overcome or turned, but how to travel on an empty money bag (and an empty stomach, as it turned out in my case), in a strange land, is a more difficult problem for most men than the quadrature of the circle.

I will pass over the first few stages of my journey, which led me through Chang-chia k'ou to the great emporium of eastern Mongolia, Kuei-hua Ch'eng, where I arrived on the 18th of December.

This town was known in the T'ang period (A. D. 618-907), and how long before that I can not now say.

Col. Yule thinks it was Tenduc, the capital of Prester John; but in this I can not quite agree, as I believe the latter town is to be identified with the present Tou Ch'eng (in Mongol Togto), at the mouth of the Hei-ho, which flows by Kuei-hua and empties into the Yellow River (Huang-ho) at the former place.

Father Gerbillon visited Kuei-hua Ch'eng in 1688, in the suite of the great Emperor K'ang-hsi. He describes the place as follows: "C'est une petite Ville qu'on dit avoir été autrefois fort marchande, et d'un grand abord, pendant que les Tartares d'Oüest étoient les maîtres de la Chine: à présent c'est fort peu de chose: les murailles bâties de briques sont assez entières par dehors; mais il n'y a plus de remparts au dedans: il n'y a même rien de remarquable dans la Ville, que les Pagodes et les Lamas." t

* See his Book of Ser Marco Polo, 2d edit., 1, 277.

+ Du Halde, "Description de l'Empirede la Chine," IV, 103. The Mongol name of this town is Koko hutun, or "Blue town." Chinese histories of the seventh century mention it under the name of Tung-shou Chiang.

In 1844, Father Huc, when on his way to Lh'asa, stopped for a while at Kuei-hua Ch'eng. He says of it: "With the exception of the lamaseries, which rise above the other buildings, one only sees an agglomeration of houses and shops huddled together without order, the one against the other. The ramparts of the old city still exist in their entirety, but the overflow of the population has been forced to cross them. Little by little numerous houses have been built outside the walls, vast quarters have been formed; and now the extra muros has acquired more importance than the city itself."*

Fifty years hardly count in the life of an inland city in Asia, and Kuei-hua to-day is what it was in the days of Huc-an irregular mass of tumble-down houses built around a small central walled town. Dirty, muddy, unpaved streets, innumerable small shops, crowded streets along which loaded camels and mules and clumsy carts are moving, and where an occasional Mongol, very often much the worse for liquor, is seen accompanied by his women folk in green satin dresses and much jewelry of silver and numerous strings of coral beads ornamenting their hair, neck, and ears.

The chief industry of the place is, and has been for at least a century, the preparation of sheep and goat skins. Tallow is also an important article of trade, and sheep and camels in vast numbers are annually sold here to supply the Peking market. The population, exculsively Chinese, of this place is probably between 75,000 and 100,000.

On the 25th of December, having completed arrangements for continuing my journey to Ning-hsia Fu in Kan-su in commodious carts like those which had brought me thus far on my way, I left Kuei-hua and in two days reached the Yellow River at Ho-k'ou, where it makes a sharp bend southward.

Crossing the river-here about 400 yards wide-on the ice, we first travelled over a country with sand dunes intersecting it here and there, and finally entered the vast alluvial plains which stretch westward to Alashan and are bounded to the north-on the left bank of the river, by a range of mountains of an average altitude of some 1,800 feet. This chain is called on European maps the Inshan (a corruption, I believe, of Ch'ing shan, a name given to the eastern part of it) and is locally known by a variety of names-as are all ranges in eastern Asia-Ta ch'ing shan, Wula shan, Lang shan, etc.‡

For thirteen days we travelled through the sandy waste, now and then passing a small village of Chinese colonists settled in these Mongol lands, where they cultivate the soil after a great expenditure of labor on vast irrigation ditches, which are necessary to water the parched soil and which the sands, driven before the nearly incessant

Huc, "Souvenirs d'un voyage damns la Tartarie et le Thibet," (12mo. edit.) I,

+ Huc's Tchagan Kouren, See op. cit., 1, 215.

Timkowski, "Voy. a Peking," 11, 265, 267, says this range is called Khadjar Khosho (Khajar hosho), or Onghin oola.