This is an appeal from the order of the lower court denying appellant Martin Wansley’s petition for a writ of habeas corpus. For the reasons developed below, we reverse.

The pertinent facts of this case may be summarized as follows: On May 28,1976, appellant was arrested for certain violations of The Controlled Substance, Drug, Device and Cosmetic Act. He was arraigned on that date, and the District Justice scheduled a preliminary hearing for June 2, 1976;1 bail, although set at $10,000, was not posted. Appellant was present at this preliminary hearing and was granted a continuance until June 11 since his attorney was out of the country. On June 11, the District Justice further continued appellant’s preliminary hearing because he had been advised that two of the Commonwealth’s witnesses would be appearing in a court session in Allegheny County. No date was scheduled for a subsequent hearing at that time. The testimony indicates that the District Justice, on a date not fixed, later received information from the District Attorney’s office to the effect that a Commonwealth witness had been injured in an automobile accident. Apparently, he again continued the preliminary hearing, without rescheduling it, and appellant’s bail was reduced to $7,500. Appel*237lant, however, remained incarcerated at the Blair County Prison.

On July 23, 1976, appellant petitioned the Court of Common Pleas of Blair County for a writ of habeas corpus, asking that a hearing be set for the purpose of fixing bail. A hearing on this petition was held on August 3, at which time appellant was granted leave to file an amended petition to seek his discharge. Also, on August 3, the District Justice scheduled appellant’s preliminary hearing for August 10.

On August 10, 1976, following a hearing on the amended petition, the court below entered an order denying appellant his discharge or his release upon his own recognizance. This appeal followed.

The principal function of a preliminary hearing under Pennsylvania law is to protect an individual’s right against unlawful arrest and detention. Commonwealth v. Mullen, 460 Pa. 336, 333 A.2d 755 (1975). A preliminary hearing is not a trial; its sole purpose is to determine whether a prima facie case has been made out against the accused. Commonwealth v. Smith, 232 Pa.Super. 546, 334 A.2d 741, allocatur refused, 232 Pa. Super, xxxi (1975). Rule 140(f)(1) of the Pennsylvania Rules of Criminal Procedure provides that the issuing authority shall schedule a preliminary hearing within three to ten days of the preliminary arraignment.2 This Rule is designed to prevent prolonged custody of an accused and undue delays in the disposition of the case against him. Commonwealth v. Hailey, 470 Pa. 488, 368 A.2d 1261 (1977). In effect, it provides for a speedy determination of probable cause. Commonwealth v. DeCosey, 246 Pa.Super. 412, 371 A.2d 905 (1977).

There may be circumstances in which a preliminary hearing, although originally scheduled in compliance with Rule 140(f)(1), cannot be held on the date set for it. Recog*238nizing this possibility, Rule 142 authorizes the issuing authority to grant a continuance for cause shown. That a party is properly granted a continuance for the purpose of procuring the attendance of material witnesses cannot be disputed. However, an accused must still be insured as speedy a preliminary hearing as practical;3 the necessity for preventing prolonged custody pending a determination of probable cause remains, despite the existence of valid reasons for a continuance.

Here, the Commonwealth was granted a continuance on June 11 because two of its witnesses were unavailable. It appears that the District Justice did not set a date for the continued hearing at that time, but awaited word from the Assistant District Attorney as to an acceptable date. Moreover, the docket is silent as to the continuance subsequently granted because of the injuries sustained by a Commonwealth witness.4 Appellant, however, was incarcerated at the Blair County Prison during this entire period.

In Commonwealth v. DeCosey, supra, we recognized that incarceration is one of the obvious prejudices to an accused resulting from a delay in the scheduling of his preliminary hearing. We held in that case that discharge was not the appropriate remedy for non-compliance with Rule 140(f)(1) since the defendant had been released on bail and could not show any prejudice resulting from a four-day delay in the original scheduling of his hearing apart from the delay *239itself. Here, however, appellant’s extended incarceration while awaiting the rescheduling of his preliminary hearing supplies the element of prejudice we found lacking in Commonwealth v. DeCosey, supra.5

Under the circumstances, we conclude that appellant was unlawfully deprived of his liberty and was entitled to a writ releasing him from custody.

Order reversed and appellant discharged.

concurring:

I concur, but wish to reiterate my view that in a case in which there has been something other than “substantial compliance” with Rule 140(f) (as in the present case), a defendant need not show prejudice. Commonwealth v. DeCosey, 246 Pa.Super. 412, 418, 371 A.2d 905, 907 (1977) (Concurring Opinion by SPAETH, J.).