Two historical novels for young adults. Stories transport readers back to Civil War and time of Napoleon

The Tamarack Tree, by Patricia Clapp. New York: Lothrop, Lee & Shepard Books. 214 pp. $10.95. Ages 12 and up. ``The Tamarack Tree'' tells the story of Tad, a transplanted English girl living in Vicksburg, Miss., during the Civil War -- or, as Southerners prefer to call it, the War Between the States.

This historical novel for young adults may appeal to older adults as well. It's a thoughtful piece of writing that accurately reflects both the time and place of its telling.

The tale is told by Rosemary -- or Tad, as her older brother calls her. She is writing down the details of her everyday life in America during the 47-day siege of Vicksburg in the spring of 1863.

As an English girl, Tad sides emotionally with the Northerners' view that slavery is evil. Yet she loves the Southerners she has met and understands that many of them treat their slaves with kindness.

Her brother Derek sides with the Northerners in their cause by aiding the Underground Railroad, the network of hiding places that helped slaves escape from the South to the North.

The author presents the views of both sides in the civil conflict and gives the reader some background on slave trading, observing:

``Slave trading is a business like any other. It makes money. And there were no laws against it. Slavery is as old as time. There were slaves in all the British colonies and in most other countries at one period or another. White slaves as well as blacks.''

Hector, a free black man who works for Tad's uncle, gives yet another view of slavery when he talks about the African tribes that sell members of other tribes captured during tribal wars to white men to use as slaves.

Tad's diary is not just about the war and the siege of Vicksburg; it also reflects the thoughts of a typical teen-age girl: romance, dresses, parties, shopping trips, girl talk.

As she buys material for her dresses, falls in love with a Northern soldier, and describes her friendship with Mary Byrd, Tad's account will strike a familiar chord with girls today.

Some may feel that this is more a girl's book than a boy's.

When dealing with the siege of Vicksburg, for example, ``Tamarack Tree'' does not take us to the cannon's mouth and the front-line soldiers, but instead takes us to visit the hospitals where Tad attends the wounded and dying.

But both boys and girls can relate to descriptions of the deprivation that the war causes soldiers, as well as the citizens of Vicksburg.

There's even a recounting of President Abraham Lincoln's plan to cut the South in half by controlling the Mississippi River and preventing boats carrying supplies from the North from getting through to the Southern states.

Author Patricia Clapp's first novel, ``Constance: A Story of Early Plymouth,'' was runner-up for the 1969 National Book Award for Children's Literature, and another book, ``Witches' Children,'' was selected as an American Library Association Best Book for Young Adults.

This title will likely end up on a ``best'' list, as well. The Ship From Simnel Street, by Jenny Overton. New York: Greenwillow Books. 144 pp. $10.25. Ages 12 and up.

``The Ship from Simnel Street'' is another historical novel that may appeal most to teen-age girls.

Although the setting is London during the Peninsular War (1808-14) and the heroine is an English baker's daughter who follows her sweetheart to Lisbon, where he is fighting Napoleon's Army, the war plays a minor role in the story.

It's the bakery on Simnel Street that takes center stage. (A simnel is a rich fruitcake traditionally baked and eaten during mid-Lent, Easter, and Christmas in England.)

Much of the book describes what's cooking at the bakery, with a sprinkling of the social life and customs of London's working classes during the early 19th century thrown into the mix.

Unfortunately, what's presented here is an appeti zer that only whets our taste for a more satisfying meal.