SOUTHERN INDIANA GAS AND ELECTRIC COMPANY

                                      WITH

                             BANKERS TRUST COMPANY,

                                   as Trustee

                             SUPPLEMENTAL INDENTURE

                        Providing among other things for

                              FIRST MORTGAGE BONDS

                    ___% Senior Note Series of 1999 due 20__

                            Dated as of July __, 1999


            SUPPLEMENTAL INDENTURE, dated as of July __, 1999, between SOUTHERN
INDIANA GAS AND ELECTRIC COMPANY, a corporation organized and existing under the
laws of the State of Indiana (hereinafter called the "Company"), party of the
first part, and BANKERS TRUST COMPANY, a corporation organized and existing
under the laws of the State of New York, as Trustee under the Mortgage
hereinafter referred to, party of the second part.

            WHEREAS, the Company heretofore executed and delivered to Bankers
Trust Company, as Trustee (hereinafter called the "Trustee"), a certain
Indenture of Mortgage and Deed of Trust dated as of April 1, 1932, to secure an
issue of bonds of the Company, issued and to be issued in series, from time to
time, in the manner and subject to the conditions set forth in the said
Indenture, and the said Indenture has been amended and supplemented by
Supplemental Indentures dated as of August 31, 1936, October 1, 1937, March 22,
1939, July 1, 1948, June 1, 1949, October 1, 1949, January 1, 1951, April 1,
1954, March 1, 1957, October 1, 1965, September 1, 1966, August 1, 1968, May 1,
1970, August 1, 1971, April 1, 1972, October 1, 1973, April 1, 1975, January 15,
1977, April 1, 1978, June 4, 1981, January 20, 1983, November 1, 1983, March 1,
1984, June 1, 1984, November 1, 1984, July 1, 1985, November 1, 1985, June 1,
1986, November 15, 1986, January 15, 1987, December 15, 1987, December 13, 1990,
April 1, 1993, May 1, 1993 and June 1, 1993, which Indenture as so amended and
supplemented is hereinafter referred to as the "Mortgage" and as further
supplemented by this Supplemental Indenture is hereinafter referred to as the
"Indenture"; and

            WHEREAS, the Mortgage provides that the Company and the Trustee may,
from time to time, enter into such indentures supplemental to the Mortgage as
shall be deemed by them necessary or desirable, to establish the terms and
provisions of any series of bonds to be issued under said Mortgage and to add to
the covenants and agreements of the Company for the protection of the holders of
bonds and of the mortgaged and pledged property; and

            WHEREAS, the Company and the Trustee deem it necessary or desirable
to enter into this Supplemental Indenture for such purposes; and

            WHEREAS, the Company by appropriate corporate action in conformity
with the terms of the Indenture has duly determined to create a series of bonds
to be issued under the Indenture to be designated as "First Mortgage Bonds, ___%
Senior Note Series of 1999 due 20__" (hereinafter sometimes referred to as
"bonds of the Thirty-Eighth Series"), the bonds of which series are to bear
interest at the rate per annum set forth in the title thereof; and

            WHEREAS, the definitive registered (without coupons) bonds of the
Thirty-Eighth Series and the Trustee's certificate of authentication to be borne
by such bonds are to be substantially in the following forms, respectively:

           [FORM OF FULLY REGISTERED BOND OF THE THIRTY-EIGHTH SERIES]

                             [FORM OF FACE OF BOND]


                    SOUTHERN INDIANA GAS AND ELECTRIC COMPANY

              FIRST MORTGAGE BOND, ___% SENIOR NOTE SERIES OF 1999

                                    DUE 20__

No. _______                                                         $ __________

            Southern Indiana Gas and Electric Company, a corporation of the
State of Indiana (hereinafter called the "Company"), for value received, hereby
promises to pay to ______________________________ or registered assigns
______________________________ dollars, on July __, 20__ at the office or agency
of the Company in the Borough of Manhattan, The City of New York, New York, in
any coin or currency of the United States of America which at the time of
payment is legal tender for the payment of public and private debts, and to pay
to the registered owner hereof interest thereon from the interest payment date
(________ 1 or ________ 1) next preceding the date of this bond unless the date
hereof is prior to ________ 1, 1999, in which case from ________ 1, 1999 (or, of
this bond is dated between the record date for any interest payment date and
such interest payment date, then from such interest payment date), at the rate
of _____________ per cent (__%) per annum in like coin or currency, payable at
said office or agency on ________ 1 and ________ 1 in each year, until the
Company's obligation with respect to the payment of such principal shall have
been discharged. The interest so payable on any ________ 1 or ________ 1 will,
subject to certain exceptions provided in the Mortgage hereinafter mentioned, be
paid to the person in whose name this bond is registered at the close of
business on the record date, which shall be the ________ 15 or ________ 15, as
the case may be, next preceding such interest payment date, or, if such ________
15 or ________ 15 shall be a legal holiday or a day on which banking
institutions in the Borough of Manhattan, The City of New York, New York, are
authorized or obligated by law to close, the next preceding day which shall not
be a legal holiday or a day on which such institutions are so authorized or
obligated to close.

            The provisions of this bond are continued on the reverse hereof and
such continued provisions shall for all purposes have the same effect as though
fully set forth at this place.

            This bond shall not become obligatory until Bankers Trust Company,
the Trustee under the Mortgage, or its successor thereunder, shall have signed
the form of certificate endorsed hereon.

            IN WITNESS WHEREOF, Southern Indiana Gas and Electric Company has
caused this bond to be signed in its name by its President or a Vice President,
by his signature or a facsimile thereof, and a facsimile of its corporate seal
to be imprinted hereon, attested by its Secretary or an Assistant Secretary, by
his signature or a facsimile thereof.


                                       2


Dated:

                                        SOUTHERN INDIANA GAS AND
                                          ELECTRIC COMPANY

                                        By:
                                           -------------------------------------
                                              Name:
                                              Title: President and
                                                     Chief Executive Officer


Attest:

- -------------------------------
           Secretary


                                       3


                         [FORM OF TRUSTEE'S CERTIFICATE]

            This bond is one of the bonds of the series designated therein,
described in the within-mentioned Mortgage.

                                        BANKERS TRUST COMPANY,
                                         as Trustee,

                                        By:
                                           -------------------------------------
                                              Name:
                                              Title:

                            [FORM OF REVERSE OF BOND]

                    SOUTHERN INDIANA GAS AND ELECTRIC COMPANY

          FIRST MORTGAGE BOND, __% SENIOR NOTE SERIES OF 1999 DUE 20__

            This bond is one of an issue of First Mortgage Bonds of the Company,
issuable in series, and is one of the series designated in the title hereof, all
issued and to be issued under and equally secured (except as to any sinking fund
established in accordance with the provisions of the Mortgage hereinafter
mentioned for the bonds of any particular series) by an Indenture of Mortgage
and Deed of Trust, dated as of April 1, 1932, executed by the Company to Bankers
Trust Company, as Trustee, as amended and supplemented by indentures
supplemental thereto, to which Indenture as so amended and supplemented (herein
referred to as the Mortgage) reference is made for a description of the property
mortgaged and pledged, the nature and extent of the security, the rights of the
holders of the bonds in respect thereof and the terms and conditions upon which
the bonds are secured.

            The principal hereof may be declared or may become due on the
conditions, with the effect, in the manner and at the time set forth in the
Mortgage, upon the occurrence of a completed default as provided in the
Mortgage.


                                       4


            The bonds of this series shall be redeemable as follows: [     ]


                                       5


            This bond is transferable as prescribed in the Mortgage by the
registered owner hereof in person, or by his duly authorized attorney, at the
office or agency of the Company in the Borough of Manhattan, The City of New
York, New York, upon surrender and cancellation of this bond, and thereupon, a
new fully registered bond of the same series for a like principal amount will be
issued to the transferee in exchange thereof as provided in the Mortgage, and
upon payment, if the Company shall require it, of the charges therein
prescribed. The Company and the Trustee may deem and treat the person in whose
name this bond is registered as the absolute owner for the purpose of receiving
payment of or on account of the principal, premium, if any, and interest due
hereon and for all other purposes.

            The bonds of this series are issuable as registered bonds without
coupons in denominations of $1,000 and authorized multiples thereof. In the
manner and upon payment of the charges prescribed in the Mortgage, registered
bonds without coupons of this series may be exchanged for a like aggregate
principal amount of registered bonds without coupons of other authorized
denominations of the same series, upon presentation and surrender thereof, for
cancellation, to the Trustee at its principal corporate trust office in the
Borough of Manhattan, The City of New York, New York.

            No recourse shall be had for the payment of the principal of,
premium, if any, or interest on this bond against any incorporator or any past,
present or future subscriber to the capital stock, stockholder, office or
director of the Company or of any predecessor or successor corporation, either
directly or through the Company or any predecessor or successor corporation,
under any rule of law, statute or constitution or by the enforcement of any
assessment or otherwise, all such liability of incorporators, subscribers,
stockholders, officers and directors being released by the holder or owner
hereof by the acceptance of this bond and being likewise waived and released by
the terms of the Mortgage.

            Pursuant to the Mortgage, the holder or owner of this bond by his
acceptance hereof is deemed to have agreed to amendments to the Mortgage which
will eventually permit certain amendments to the Mortgage with the consent of
the holders of 66% of the principal amount of the outstanding bonds of all
series issued under the Mortgage, which redefine, effective at such time as all
bonds of each series of bonds issued under the Mortgage prior to January 1, 1977
are no longer outstanding, the amounts required to be spent by the Company under
the Mortgage for the repair, maintenance, renewal and replacement of its
property and which authorize the Company, effective at such time as all bonds of
each series issued under the Mortgage on or prior to May 31, 1986 are no longer
outstanding, to designate bonds of any series as the bonds to be redeemed
pursuant to Section 36B of the Mortgage and to do so at any time that cash for
such purpose is on deposit with Trustee pursuant to the provisions of that
Section.

                              [END OF FORM OF BOND]


                                       6


and

            WHEREAS, all things necessary to make the bonds of the Thirty-Eighth
Series, when authenticated by the Trustee and issued as in the Indenture
provided, the valid, binding and legal obligations of the Company, entitled in
all respects to the security of the Indenture, have been done and performed, and
the creation, execution and delivery of this Supplemental Indenture has in all
respects been duly authorized; and

            WHEREAS, the Company and the Trustee deem it advisable to enter into
this Supplemental Indenture for the purposes above stated and for the purpose of
describing the bonds of the Thirty-Eighth Series, and of providing the terms and
conditions of redemption thereof;

            NOW, THEREFORE, THIS SUPPLEMENTAL INDENTURE WITNESSETH: That
Southern Indiana Gas and Electric Company, in consideration of the premises and
of one dollar to it duly paid by the Trustee at or before the ensealing and
delivery of these presents, the receipt whereof is hereby acknowledged, and of
the purchase and acceptance of the bonds issued or to be issued hereunder by the
holders or registered owners thereof, and in order to secure the payment of the
principal, premium, if any, and interest of all bonds at any time issued and
outstanding under the Indenture, according to their tenor and effect, and the
performance of all of the provisions hereof and of said bonds, hath granted,
bargained, sold, released, conveyed, assigned, transferred, pledged, set over
and confirmed and by these presents doth grant, bargain, sell, release, convey,
assign, transfer, pledge, set over and confirm unto Bankers Trust Company, as
Trustee, and to its successor or successors in said trust, and to its and their
assigns forever, all the properties of the Company located in the State of
Indiana described in Schedule A (which is identified by the signature of an
officer of each party hereto at the end thereof) hereto annexed and hereby made
a part hereof and does hereby confirm that the Company will not cause or consent
to a partition, either voluntary or through legal proceedings, of property,
whether herein described or heretofore or hereafter acquired, in which its
ownership shall be as a tenant in common, except as permitted by and in
conformity with the provisions of the Indenture and particularly of Article X
thereof.

            TOGETHER WITH all and singular the tenements, hereditaments and
appurtenances belonging or in any wise appertaining to the aforesaid property or
any party thereof, with the reversion and reversions, remainder and remainders
and (subject to the provisions of Article X of the Indenture), the tolls, rents,
revenues, issues, earnings, income, product and profits thereof, and all the
estate, right title interest and claim whatsoever, at law as well as in equity,
which the Company now has or may hereafter acquire in and to the aforesaid
property and franchises and every part and parcel thereof.

            TO HAVE AND TO HOLD all such properties, real, personal and mixed,
mortgaged, pledged or conveyed by the Company as aforesaid, or intended so to
be, unto the Trustee and its successors and assigns forever.


                                       7


            IN TRUST, NEVERTHELESS, upon the terms and trusts of the Indenture,
for those who shall hold the bonds and coupons issued and to be issued
thereunder, or any of them, without preference, priority or distinction as to
lien of any of said bonds and coupons over any others thereof by reason of
priority in the time of the issue or negotiation thereof, or otherwise
howsoever, subject, however, to the provisions in reference to extended,
transferred or pledged coupons and claims for interest set forth in the
Indenture (and subject to any sinking funds that may be created for the benefit
of any particular series).

            PROVIDED, HOWEVER, and these presents are upon the condition that,
if the Company, its successors or assigns, shall pay or cause to be paid, the
principal of, premium, if any, and interest on said bonds, at the times and in
the manner stipulated therein and herein, and shall keep, perform and observe
all and singular the covenants and promises in said bonds and in the Indenture
expressed to be kept, performed and observed by or on the part of the Company,
then this Supplemental Indenture and the estate and rights hereby granted shall
cease, determine and be void, otherwise to be and remain in full force and
effect.

            IT IS HEREBY COVENANTED, DECLARED AND AGREED, by the Company, that
all such bonds and coupons are to be issued, authenticated and delivered, and
that all property subject or to become subject hereto is to be held, subject to
the further covenants, conditions, uses and trusts in the Indenture set forth,
and the Company, for itself and its successors and assigns, does hereby covenant
and agree to and with the Trustee and its successor or successors in such trust,
for the benefit of those who shall hold said bonds and interest coupons, or any
of them, as follows:

            SECTION 1. Bonds of the Thirty-Eighth Series shall mature on the
date set forth in the form of bond relating thereto hereinbefore set forth,
shall bear interest at the rate per annum set forth in the title thereof,
payable semi-annually, on ________ 1 and ________ 1 in each year, and all bonds
of said series shall be designated as hereinbefore in the fourth Whereas clause
set forth. Principal of, premium, if any, and interest on said bonds shall be
payable in any coin or currency of the United States of America which at the
time of payment is legal tender for the payment of public and private debts, at
the office or agency of the Company in the Borough of Manhattan, The City of New
York, New York. Definitive bonds of said series may be issued, originally or
otherwise, only as registered bonds without coupons; and they and the Trustee's
certificate of authentication shall be substantially in the forms hereinbefore
recited, respectively. Definitive registered bonds of the Thirty-Eighth Series
may be issued in the denomination of $1,000 and in such other denominations (in
multiples of $1,000) as the Board of Directors of the Company shall approve, and
execution and delivery to the Trustee for authentication shall be conclusive
evidence of such approval. In the manner and upon payment of the charges
prescribed in the Indenture, registered bonds without coupons of said series may
be exchanged for a like aggregate principal amount of registered bonds without
coupons of other authorized denominations of the same series, upon presentation
and surrender thereof for cancellation to the Trustee at its principal corporate
trust office in the Borough of Manhattan, The City of New York, New York.
However, notwithstanding the provisions of Section 12 of the Indenture, no
charge shall be made upon any transfer or exchange of bonds of said series other
than for any tax


                                       8


or taxes or other governmental charge required to be paid by the Company. The
form of the temporary bonds of said series shall be in substantially the form of
the form of registered bond hereinbefore recited with such appropriate changes
therein as are required on account of the temporary nature thereof. Said
temporary bonds of said series shall be in registered form without coupons and
shall be exchangeable for definitive bonds of said series when prepared.

            The person in whose name any registered bond without coupons of the
Thirty-Eighth Series is registered at the close of business on any record date
(as hereinbelow defined) with respect to any interest payment date shall be
entitled to receive the interest payable on such interest payment date
notwithstanding the cancellation of such registered bond upon any transfer or
exchange thereof subsequent to the record date and prior to such interest
payment date, except if and to the extent the Company shall default in the
payment of the interest due on such interest payment date, in which case such
defaulted interest shall be paid to the person in whose name such bond is
registered either at the close of business on the day preceding the date of
payment of such defaulted interest or on a subsequent record date for such
payment if one shall have been established as hereinafter provided. A subsequent
record date may be established by or on behalf of the Company by notice mailed
to the holders of bonds not less than ten days preceding such record date, which
record date shall be not more than thirty days prior to the subsequent interest
payment date. The term "record date" as used in this Section with respect to any
regular interest payment date shall mean the ________ 15 or ________ 15, as the
case may be, next preceding such interest payment date, or, if such ________ 15
or ________ 15 shall be a legal holiday or a day on which banking institutions
in the Borough of Manhattan, The City of New York, New York, are authorized or
obligated by law to close, the next preceding day which shall not be a legal
holiday or day on which such institutions are so authorized or obligated to
close.

            Except as provided in this Section, every registered bond without
coupons of the Thirty-Eighth Series shall be dated and shall bear interest as
provided in Section 10 of the Indenture; provided, however, that so long as
there is no existing default in the payment of interest on the bonds, the holder
of any bond authenticated by the Trustee between the record date for any
interest payment date and such interest payment date shall not be entitled to
the payment of the interest due on such interest payment date and shall have no
claim against the Company with respect thereto; and provided, further, that, if
and to the extent the Company shall default in the payment of the interest due
on such interest payment date, then any such bond shall bear interest from the
________ 1 or ________ 1, as the case may be, next preceding the date of such
bond, to which interest has been paid or, if the Company shall be in default
with respect to the interest due on ________ 1, 1999, then from ________ 1,
1999.

            Bonds of the Thirty-Eighth Series shall be redeemable as follows:
[     ]


                                       9


            SECTION 2. The Company's obligation to make payments with respect to
the principal of, premium, if any, and/or interest on, the bonds of the
Thirty-Eighth Series shall be fully or partially satisfied and discharged to the
extent that, at the time any such payment shall be due, the corresponding amount
then due of principal of, and/or premium, if any, and/or interest then due on,
the senior notes (the "Senior Notes") issued pursuant to the Indenture (for
Senior Notes) dated as of July __, 1999, between the Company and Bankers Trust
Company, the Senior Note Trustee (the "Senior Note Indenture") shall have been
fully or partially paid (other than by the application of the proceeds of a
payment in respect of such bonds of the Thirty-Eighth Series), as the case may
be, or there shall have been deposited with the Senior Note Trustee pursuant to
the Senior Note Indenture trust funds sufficient under such indenture to fully
or partially pay, as the case may be, the corresponding amount then due of
principal of, and/or premium, if any, and/or interest on, the Senior Notes
(other than by the application of the proceeds of a payment in respect of such
bonds of the Thirty-Eighth Series).

            Upon payment of the principal of, and premium if any, and interest
due on the Senior Notes, whether at maturity or prior to maturity by
acceleration, redemption or otherwise, or upon provision for the payment thereof
having been made in accordance with the Senior Note Indenture (other than by the
application of the proceeds of a payment in respect of such bonds of the
Thirty-Eighth Series), bonds of the Thirty-Eighth Series in a principal amount
equal to the principal amount of Senior Notes so paid or for which such
provision for payment has been made shall be deemed fully paid, satisfied and
discharged and the obligations of the Company thereunder shall be terminated and
such bonds of the Thirty-Eighth Series shall be surrendered to and cancelled by
the Trustee. From and after the Release Date (as defined in the Senior Note
Indenture), the bonds of the Thirty-Eighth Series shall be deemed fully paid,
satisfied and discharged and the obligation of the Company thereunder shall be
terminated. On the Release Date, the bonds of the Thirty-Eighth Series shall be
surrendered to and cancelled by the Trustee.

            SECTION 3. The Company covenants that the provisions of Section 36A
of the Indenture and of Section 1.02 of the Supplemental Indenture dated as of
July 1, 1948, which are to remain in effect so long as any bonds of the series
referred to in said Section shall be outstanding under the Indenture, shall
remain in full force and effect so long as any bonds of the Thirty-Eighth Series
shall be outstanding under the Indenture.

            SECTION 4. Except as herein otherwise expressly provided, no duties,
responsibilities or liabilities are assumed, or shall be construed to be
assumed, by the Trustee by reason of this Supplemental Indenture, other than as
set forth in the Mortgage. The Trustee shall not be responsible for the recitals
herein or in the bonds (except the Trustee's certificate of authentication), all
of which are made by the Company solely. Without limiting the generality of the
foregoing, the Trustee shall have no responsibility for, and shall incur no
liability with respect to, the form or substance of the Certificates or the form
or substance of any agreement under which any banking or other financial
institution receives the Deposit or makes the Payments nor shall the Trustee
have any responsibility, or incur any liability, with respect to the performance
of such banking or other financial institution under any such agreement.


                                       10


            SECTION 5. As supplemented and amended by this Supplemental
Indenture, the Mortgage is in all respects ratified and confirmed, and the
Mortgage and this Supplemental Indenture shall be read, taken and construed as
one and the same instrument.

            SECTION 6. This Supplemental Indenture may be executed in several
counterparts and all such counterparts executed and delivered, each as an
original, shall constitute but one and the same instrument.


                                       11


            IN WITNESS WHEREOF, SOUTHERN INDIANA GAS AND ELECTRIC COMPANY, party
of the first part hereto, and BANKERS TRUST COMPANY, party of the second part
hereto, have caused these presents to be executed in their respective names by
their respective Chairmen of the Board or Presidents or one of their Vice
Presidents or Assistant Vice Presidents and their respective seals to be
hereunto affixed and attested by their respective Secretaries or one of their
Assistant Secretaries, all as of the day and year first above written.

(SEAL)                                  SOUTHERN INDIANA GAS AND
                                         ELECTRIC COMPANY,

                                        By:
                                            ------------------------------------
                                            Name:
                                            Title:


Attest:


- -----------------------
Name:
Title:


(SEAL)                                  BANKERS TRUST COMPANY,

                                        By:
                                            ------------------------------------
                                            Name:
                                            Title:


Attest:


- -----------------------
Name:
Title:


                                       12


STATE OF INDIANA        )
                        )     ss.:
COUNTY OF VANDERBURGH   )

            On this __ day of July, 1999, before me, the undersigned, a notary
public in and for the county and state aforesaid, personally came
___________________, to me known, who being by me duly sworn, did depose and say
that he resides at _________________________________; that he is
_____________________ of SOUTHERN INDIANA GAS AND ELECTRIC COMPANY, one of the
corporations described in and which executed the foregoing instrument; that he
knows the seal of the said corporation; that the seal affixed to said instrument
is such corporate seal; that it was so affixed by order of the Board of
Directors of said corporation and that he signed his name thereto by like order;
and the said _____________________ acknowledged the execution of the foregoing
instrument on behalf of the said corporation as the voluntary act and deed of
the said corporation for the uses and purposes therein set forth.

            IN WITNESS WHEREOF, I have hereunto set my hand and seal the day and
year first above written.

(SEAL)                                  --------------------------
                                        Notary Public

My Commission Expires

My County of Residence is


                                       13


STATE OF NEW YORK       )
                        )     ss.:
COUNTY OF NEW YORK      )

            On this __ day of July, 1999, before me, the undersigned, a notary
public in and for the county and state aforesaid, personally came
___________________, to me known, who being by me duly sworn, did depose and say
that he resides at ____________________________; that he is a
______________________ of BANKERS TRUST COMPANY, one of the corporations
described in and which executed the foregoing instrument; that he knows the seal
of the said corporation; that the seal affixed to said instrument is such
corporate seal; that it was so affixed by order of the Board of Directors of
said corporation and that he signed his name thereto by like order; and the said
______________________ acknowledged the execution of the foregoing instrument on
behalf of the said corporation as the voluntary act and deed of the said
corporation for the uses and purposes therein set forth.

            IN WITNESS WHEREOF, I have hereunto set my hand and seal the day and
year first above written.

(SEAL)                                  --------------------------
                                        Notary Public

My Commission Expires

My County of Residence is


                                       14


                                      A-1

                                   SCHEDULE A

                  Detailed Description of Additional Properties

                                        Signed for identification


                                        ----------------------------------------
                                        Name:
                                        Title:
                                        SOUTHERN INDIANA GAS AND ELECTRIC
                                          COMPANY



                                        ----------------------------------------
                                        Name:
                                        Title:
                                        BANKERS TRUST COMPANY


                                       15