EF. Loomis— Observations of the U. S. Signal Service. 15 
no longer be traced, while others change their course and turn 
towards the northeast. In my eleventh paper I have shown 
that storms which advance from north to south across the Uni- 
ted States, are generally attended by a very slight fall of rain; 
and this seems to explain the fact that they generally decline 
in intensity as they advance southward. 
Storms in the Middle latitudes advancing in a Westerly direction. 
The infrequency of the cases in which tropical storms have 
advanced towards the southwest, has led me to search for cor- 
responding cases in the middle latitudes of America and Eu- 
rope. For this purpose I have examined all the cases in which 
the charts of the U. S. Signal Service indicate the movement of 
a storm center towards any westerly point. I have also exam- 
ined Hoffmeyer’s daily charts from Dec., 1873, to Oct., 1876; 
the charts of the Deutsche Seewarte from Jan., 1876, to March, 
1879, and from Jan., 1880, to April, 1880; also the charts of 
the International Observations from Nov., 1877, to Dec., 1879. 
any of the cases of this description which are shown on the 
charts of the U. S. Signal Service are cases in which the depres- 
sion of the barometer was small, when there was no single well- 
efined storm center, but there were two or three centers of 
slight depression within a few hundred miles of each other, so 
that a slight change in the force of the winds would cause one 
of the centers to predominate a little, and thus the center of 
greatest depression might be carried in an unusual direction. 
The following table shows the most decided cases in which 
storm-centers in the United States have advanced in a westerly 
direction : 
Storms in the United States advancing Westerly. 
Raye ite Beg: end pew. ena] Course. |miies barom.| "eouee. 
1/1873. Oct. 20.1-21.3 | 39-46 | 75-86} N.W. | 20-7 | 29°35 |Unknown 
2}1874. May 9.1- 9.3| 49-42 |97-104| S.W. |37°3| ‘29 \N.E. 
3/1876. Jan. 8.3— 9.1 |443-43| 84-87] S.W. |22°2| +14 |E.NLE. 
4 Feb. 25.3-26.3 |41-384) 95-97| S.S.W. | 85] -40 |Eastward 
5 June 17.3-18.2 | 44 Worst): 734 esi 
6 pt. 16.1-17,3 | 25-41 |77-794| N.N.W. | 28°8| “47 |Eastwa 
7/1877. Feb. 21.2-22.1 |48-41}| 89-93] SS.W. |33°9| 35 |Eastward 
8 Ov. 22.3-24.3 | 32-42 |794-84| N.N.W.|15°7| 63 |Disappeared 
9/1878. Feb. 19.2-20.1| 43-34 | 95-98 | S.S.W. | 43°0 3 |N.E. 
Mar. 10.1-11.1 | 43 6-104] W.S.W. |18°0| -47 |Eastward 
1 Mar. 23.1-24.1 | 50-42 |574-72) S.W. |36°7| ‘22 |E.N.E. 
12 April 28,2-29.1 | 37-41 |77-794] N.N.W. | 18°5| 58 |Disappeared 
13|___ June 22.2-23.1 | 42-44 | 76-79 | N.N.W.| 15-7 “60 |E.N.E. 
The number of these cases is 13; and 4 of these pursued a 
course about N.N.W.; 2 advanced towards the N.W.; 
towards the W.S.W.; 3 towards the S.W.; and 8 towards the 
S.S.W. Case No. 1 was particularly noticed in my sevent 
