CAPTAIN ELLIOT’S MAGNETIC SURVEY OF THE INDIAN ARCHIPELAGO. 295 
in July and August at 23 ; in September at 22 ; in October at 21 ; and in November 
at 20 hours. If the seasons are projected in curves as in Part 2 of Plate VI., we find 
in winter the minimum at 20 hours ; in spring at 21 hours ; in summer at 23 hours ; 
and in autumn back to 21 hours ; agreeing in this with the spring curve, but differing 
very materially as regards the progression of the needle eastward in the afternoon ; 
autumn and winter agreeing in this latter respect, and also spring and summer. The 
oscillation of the curve exhibits a much greater range during the winter months*; 
the autumn curve is next in extent of range and in the afternoon preserves a certain 
degree of parallelism with the winter curve ; and both these curves have the after- 
noon maximum more decidedly expressed, and have also a higher maximum than in 
the morning. The reverse of this is the case with the spring and summer curves. 
The mean curves of the three years exhibit a wonderful uniformity and almost 
total resemblance. There are two most decided maxima at 18 and at 3 or 4 hours, 
and one^minimum at 21. There are besides two other minima at 10 and at 17 hours 
more faintly expressed. If we turn to the seasons, we find only one strongly defined 
maximum and minimum or a single progression in winter; in spring two strongly 
expressed maxima and one minimum ; in summer and in autumn two maxima and 
two minima; and as these maxima and minima occur at different periods, the mean 
annual curve thus blends the leading characteristics of all, and presents accordingly 
a double, if not a triple progression. 
On an inspection of the Plates, and on comparing them with the Singapore curves, 
we find that in Part 1 of Plate IV. the Moulmein April curve resembles no single 
curve in any one month at Singapore. The curve is that described by Declinometer 
No. III. ; th^re are two minima at 17 and 1, and two maxima at 20 and 5 hours. 
Moulmein is about 8° north of the line of minimum intensity. 
The next two in Part 1 of Plate IV. are the Sambooanga May curves of Declino- 
meters Nos. I. and II.; comparing them with the same period at Singapore, we 
observe a certain degree of similarity, the morning maximum being at the same hour, 
the minimum being one hour later ; the curves of the two declinometers differ 
slightly with each other : Sambooanga is on the line of minimum intensity. 
The next curves are those of Batavia during the spring months ; their resemblance 
to the spring curve of Singapore given in Part 2 of Plate VI. is very striking ; the 
morning and afternoon maxima and the morning minimum being at the same hours 
at both places : Batavia is 14° south of the line of minimum intensity. 
The next curves in Part 1 of Plate IV. are the Sarawak summer curves ; there is a 
considerable resemblance to the curves at the same period at Singapore, the morn- 
ing minimum being one hour later ; the position of Sarawak is exactly the same as 
Singapore relatively to its position south of the line of minimum intensity. The 
* The sun is longer to the south of the line of minimum intensity than it is to the north. Singapore is in 
north latitude 1° 18', and as the line of minimum intensity crosses the meridian of Singapore in about 8° north 
latitude, the sun is to the south of it considerably more than half the year. 
