WEBER'S LECTURES

63

37.

H. F.

Weber's Lectures

on

Physics

[ca.

December 1897-ca. June

1898][1]

Vorlesungen über Physik

von

Weber.

Für

eine

auf

die

Temperatur

T erhitzte

Kugel

von

homogenem

Material,

deren Oberfläche

von

der Zeit

z

=

0

an

konstant

auf der

Temperatur t

=

0

gehalten wird,

wurde als Gesetz der

Tempera-

turverteilung

gefunden:[2]

ADS.

This document

is

written

in two

bound

notebooks. The

first,

17.5

x

21.5

cm,

consists

of

lined

white

paper.

Each

page

is

folded

to

create

an

outer

margin

of

5

cm.

The

second,

17

x

21.5

cm,

contains

squared

white

paper.

A

left

margin

of three

to five squares is

main-

tained

on

each

page.

A

number of

pages

toward the end of this notebook have been

cut

out.

The

manuscript

is

written in

ink,

with

occa-

sional additions and

changes in pencil

or

in

another

ink. Such

emendations

are

indicated

in

footnotes.

Marginal

notes in

the

original

are

printed

at

the

corresponding place

in

the

margin; diagrams

from the

original

are

usually

placed

within the

printed

text.

Some calculations written

on

the inside

back

cover

of

the

second notebook

are

printed

in note

197.

Three

pages

of research

notes,

dated

to

a

later

period,

will be

printed

in Vol-

ume 2.

Thirteen

pages

of unrelated

notes

on

mathematics,

written at the end of the second

notebook,

and

a

loose sheet of unrelated

notes

enclosed

in

the

first

notebook,

are

omitted.

[1]

Einstein's

notes

are

dated

on

the basis of

the

assumption

that

they

start

with material

discussed

about the

middle

of

the winter

se-

mester

of

1897-1898,

and end

with material

discussed about

one

month before the end of

the

summer

semester

of

1898.

This

assumption

is suggested

by a

comparison

of

Einstein's

notes

with Teucher's

(see

editorial

note,

"Einstein

as a

Student of

Physics

and

His

Notes

on

H.

F.

Weber's

Course").

[2] Teucher's

notes

indicate

that,

earlier

in

the

course,

Weber had derived the

following

solution

to

Fourier's heat

conduction

equa-

tion. The initial

temperature

T

is

now

denoted

by t0; c, p,

and

R

denote the

specific

heat,

density,

and radius of the

sphere, respectively,

and

r

is

the radial distance from

its center.

The heat

conductivity

K

is

defined

through

the

equation

dW

=

K

f(-dt/dn)dz.

f

is

the

area

through

which the

quantity

of heat dW

passes

during

the time interval

dz,

and

dt/dn is

the

gradient

of

the

temperature t

in

the

direction

normal

to

f.

lirr

2RSffl R

1V2K

e Tk~pcz

it

r

2irr

2R

Sifl

R

4ir2

__

2

r

R2

3irr

2R

R

9ir2

K

+to

e

r2

- r2