METEORIC AND ARTIFICIAL NICKEL-IRON ALLOYS. 
47 
Nickel Steel (continued). 
Number 
of 
experiment. 
Temperature. 
r 
Number 
of 
experiment. 
Temperature. 
r 
166-4 
(H = 0-434) C.G.S. 
166-4 
(H = 0-434) C.G.S. 
°C. 
°C. 
f 97 
14 
0-795 
/ 103 
12 
1-04 
1 98 
581 
3-46 
\ 104 
581 
3-83 
99 
12-5 
0-945 
/ 105 
12-5 
1-05 
100 
580 
3-74 
\ 106 
580 
3-82 
r 101 
12-5 
1-02 
107 
13 
1-05 
\ 102 
580 
3-81 
In experiments 36, 87, and 90, the permeability seemed to fall, with lapse of 
time, from the higher to the lower value; but the temperature coefficient of /x is very 
large between 650° C. and 750° C. 
In experiment 94 the permeability seemed to be rising gradually at 624° C. 
§ 4. The series of curves, given below, figs. 9 to 22, show the results ot the 
attempt to represent graphically, by continuous curves, the thermomagnetic properties 
of each material. The number of the experiment to which each point corresponds 
is shown in each of the curves drawn; but, because of the use made of the curves 
later and also because there are some relationships which cannot be represented 
graphically, it is necessary to state the connection between the tables and the curves 
at greater length than would otherwise be required. 
§ 5. Meteoric Iron (ls£ Winding ).—See fig. 9. 
The sequence of all the experiments tabulated will be clearer if an account is given 
of the reasons why they were performed in the order shown. 
The permeability at ordinary temperatures was determined, under my supervision, 
by Mr. W. H. N. James, with the results already given (see Section II., § 2, p. 27). 
The experiments over a wider temperature range, after the coils had been rewound by 
Mr. James and myself, had only extended to a few isolated measurements when it 
became impossible for him to take further part in the work. With a view to 
completing the experiments, I again set up the apparatus when time permitted and 
took the observations lettered a, b,...7i, of which the record is given in the first table. 
The observations a, b and c showed the variation of /x at the lower temperatures. 
The region in which the permeability began to rise rapidly was marked by d and e ; f, 
g and h marked the temperature range over which the permeability dropped from 
near its maximum value until it practically disappeared. The observations at i showed 
that the temperature lag in the reappearance of permeability, common to artificial 
nickel-iron alloys containing less than 25 per cent, of nickel, was shared by the 
